Physics final

What is the meaning of the word "conservation" in the law of conservation of charge?

"Conservation" in the law of conservation of charge means the total charge will not change over time

The woman in the figure creates two waves every second by shaking the slinky up and down. (a)What is the period of each wave? (b) If each wave travels 0.9meters after one complete wave cycle, what is the velocity of wave propagation?

(a) The period of each wave is 0.5s; and (b) the velocity of wave propagation is 1.8m/s

What is its magnification?

+10.0

On ice, assuming that μs=0.100, the same as for shoes on ice.

-0.195m/s2

A doctor examines a mole with a 15.0 cm focal length magnifying glass held 13.5 cm from the mole. Where is the image?

-1.35 m (on the object side of the lens).

Two identical conducting spheres are charged with a net charge of +5.0q on the first sphere and a net charge of −8.0q on the second sphere. The spheres are brought together, allowed to touch, and then separated. What is the net charge on each sphere now?

-1.5q

A particle carrying a charge of 8.0nC accelerates through a potential of ΔV=−10mV. What is the change in potential energy of the particle?

-80x10^-12J

A lightning strike can transfer as much as 1020 electrons from the cloud to the ground. If the strike lasts 2ms, what is the average electric current in the lightning?

-8kA

Using the graph, what is the runner's velocity from 4 to 10seconds?

0 m/s

The "lead" in pencils is a graphite composition with a Young's modulus of about 1×1010N/m2. Calculate the change in length of the lead in an automatic pencil if you tap it straight into the pencil with a force of 4.0 N. The lead is 0.50 mm in diameter and 60 mm long.

0.1 mm

What is the current through three resistors R=30Ω connected in series across a 10-V battery?

0.11A

What is the current through a 100-Ω resistor with 12V across it?

0.12 A

A defibrillator passes 12.0 A of current through the torso of a person for 0.0100 s. How much charge moves?

0.120 C

Rubbing your hands together warms them by converting work into thermal energy. If a woman rubs her hands back and forth for a total of 20 rubs, at a distance of 7.50 cm per rub, and with an average frictional force of 40.0 N, what is the temperature increase? The mass of tissues warmed is only 0.100 kg, mostly in the palms and fingers.

0.171ºC

A pendulum on Earth has a length of 5m. What is its frequency?

0.22 Hz

A team of six dogs pulls a sled with waxed wood runners on wet snow (µk = 0.08). The loaded sled with its rider has a mass of 210 kg. If each dog exerts an average force of 35 N applied force, what is the acceleration of the sled? (Take Earth's gravity as 9.8 m/s2

0.22 m/s2

Dolphins make sounds in air and water. What is the ratio of the wavelength of a sound in air to its wavelength in seawater? Assume air temperature is 20.0ºC

0.223

Ultrasound of intensity 1.50×102W/m2 is produced by the rectangular head of a medical imaging device measuring 3.00 by 5.00 cm. What is its power output?

0.225 W

A car weighs 2000kg. It moves along a road by applying a force on the road with a parallel component of 560N. There are two passengers in the car, each weighing 55kg. If the magnitude of the force of friction experienced by the car is 45N, what is the acceleration of the car?

0.244m/s^2

A marble rolling across a flat, hard surface at 2m/s rolls up a ramp. Assuming that g=10m/s2 and no energy is lost to friction, what will be the vertical height of the marble when it comes to a stop before rolling back down? Ignore effects due to the rotational kinetic energy.

0.2m

The arterioles (small arteries) leading to an organ, constrict in order to decrease flow to the organ. To shut down an organ, blood flow is reduced naturally to 1.00% of its original value. By what factor did the radii of the arterioles constrict? Penguins do this when they stand on ice to reduce the blood flow to their feet.

0.316

A ray of sunlight strikes the surface of a still lake at an incident angle of 30.00∘. If the index of refraction of air is 1.0003 and the index of refraction of water is 1.333, what is the angle of refraction for the ray of light?

0.3846 rad

Find the current through a person and identify the likely effect on her if she touches a 120-V AC source: If she is standing on a rubber mat and offers a total resistance of 300 kΩ.

0.400 mA, no effect

If your heart rate is 150 beats per minute during strenuous exercise, what is the time per beat in units of seconds?

0.400 s/beats

What is the internal resistance of a voltage source if the terminal voltage drops by 2.00 V when 5.00 A of current is drawn from it?

0.400 Ω

A subway train accelerates from rest to 30.0km/h in 20.0s. What is the average acceleration during that time interval?

0.42m/s^2

A spherical bacterium with a diameter of 2μm travels at a rate of 1μm/s directly downward in a flask of LB broth (viscosity = 1 x10-3 Pa x s). If the bacterium has a mass of 1x10-15 kg, what is its terminal velocity? What can you conclude about its movement?

0.5 μm/s - the bacteria is creating a mechanical force to propel itself through the broth

A man who works for a moving company is loading a box onto a moving van. He pushes a 200N box up a 5m long ramp. If he pushes with a force of 60N and the ramp is 1m high, what is the efficiency of the inclined plane?

0.67

Archimedes' principle can be used to calculate the density of a fluid as well as that of a solid. Suppose a chunk of iron with a mass of 390.0 g in air is found to have an apparent mass of 350.5 g when completely submerged in an unknown liquid. The density of iron is 7.8 g/cm3. Calculate the fluid's density and identify it.

0.79 g/cm3, ethyl alcohol

A 25kg object moves from left to right at a speed of 30km/h. What net force is required to keep this object moving in a straight line at constant speed?

0N, bc according to Newton's first law of motion, the state of rest or uniform motion does not change unless acted upon by an external force. Therefore, the body will keep moving in the same direction with a speed of 30km/h without any external force.

The skier's mass including equipment is 60.0kg. The angle of inclination of the plane is 25∘. 1) What is her acceleration if friction is negligible? 2) What is her acceleration if the frictional force is 45.0N?

1) 4.14m/s2 2) 3.39m/s2

What is the greatest average speed of blood flow that can flow in an artery of radius 2.00 mm if the flow is to remain laminar? What is the corresponding flow rate? Take the density of blood to be 1025 kg/m3 and the viscosity of blood as 2.08 ×10-3 N⋅s/m2)

1.02 m/s; 1.28×10-2 L/s

Some stove tops are smooth ceramic for easy cleaning. If the ceramic is 0.600 cm thick, the area of the pan is A = 1.54 × 10-2 m2, the stove delivers 2.26 kW of heat to its surface, and the thermal conductivity k=0.84J/s⋅m⋅°C, what is the temperature difference across it?

1.05X10^3 K

What pressure is exerted on the bottom of a 0.500-m-wide by 0.900-m-long gas tank that can hold 50.0 kg of gasoline by the weight of the gasoline in it when it is full?

1.09x10^3 N/m2

How much energy would it take to heat 0.500kg water at 70.0∘C to steam at 110.0∘C?

1.20x10^3 kJ

A man with a metal butter knife attempts to remove a piece of burning toast from his toaster and comes into contact with 120 V AC. He fortunately chose to wear rubber soled shoes that morning, so he suffers no ill effects. What is the effective resistance of the man's body?

1.20x10^5

The left ventricle of a resting adult's heart pumps blood at a flow rate of 83.0cm3/s, increasing its pressure by 110 mm Hg, its speed from zero to 30.0 cm/s, and its height by 5.00 cm. (All numbers are averaged over the entire heartbeat.) Calculate the total power output of the left ventricle. Note that most of the power is used to increase blood pressure.

1.26 W

The two children shown in the figure are balanced on a 12.0 kg seesaw. The first child has a mass of 26.0 kg and sits 1.60 m from the pivot. The center of mass of the seesaw is 0.160 m to the left of the pivot (on the side of the lighter child). (a) If the second child has a mass of 32.0 kg, how far is she from the pivot? (b) What is Fp, the supporting force exerted by the pivot? Explicitly show how you follow the steps in the Problem-Solving Strategy for static equilibrium. Restated, given: m1=26.0kg,m2=32.0kg,ms=12.0kg,

1.36 m, 686 N

What is the time period of a simple harmonic oscillator with a mass of 0.3kg and a force constant of 5N/m?

1.54s

What is the frequency of the 193-nm ultraviolet radiation used in laser eye surgery?

1.55 X10^15

During a marathon race, a runner's blood flow increases to 10.0 times her resting rate. Her blood's viscosity has dropped to 95.0% of its normal value, and the blood pressure difference across the circulatory system has increased by 50.0%. By what factor has the average radii of her blood vessels increased?

1.59

A physics teacher pushes a cart of demonstration equipment to a classroom, as in Image 4.12 Her mass is 65kg, the cart's mass is 12kg, and the equipment's mass is 7.0kg. To push the cart forward, the teacher's foot applies a force of 150N in the opposite direction (backward) on the floor. Calculate the acceleration produced by the teacher. The force of friction, which opposes the motion, is 24.0N.

1.5m/s^2

This figure shows a barometer, which is filled with mercury. The height of the column of mercury is h=1200mm. In units of atmospheres, what is the pressure P?

1.6 atm

A defibrillator sends a 6.00-A current through the chest of a patient by applying a 10,000-V potential as in the figure below. What is the resistance of the path?

1.67

A student has a displacement of 304 m north in 180 s. What was the student's average velocity?

1.7 m/s north

What is the peak electric field strength?

1.75kV/m

A 90.0-kg skydiver hanging from a parachute bounces up and down with a period of 1.50 s. What is the new period of oscillation when a second skydiver, whose mass is 60.0 kg, hangs from the legs of the first, as seen in the figure.

1.94 s

Suppose you apply several different voltages across a circuit and measure the current that runs through the circuit. A plot of your results is shown below. What is the resistance of the circuit?

1000

This figure shows a hydraulic lift. The force F1 has a magnitude of 100 N, and the area A1 is 0.01m2. If the area A2 is 1.0m2, what is the weight of the truck?

10000 N

How much force needs to be applied to a 5kg object for it to accelerate at 20m/s2?

100N

Using energy considerations, calculate the average force a 60.0-kg sprinter exerts backward on the track to accelerate from 2.00 to 8.00 m/s in a distance of 25.0 m, if he encounters a headwind that exerts an average force of 30.0 N against him. a

102 N

Assuming the accuracy with which this EM radiation can ablate the cornea is inversely proportional to wavelength, how much more accurate can this UV be than the shortest visible wavelength of light?

107% more accurate

If a warm spring day reaches a peak temperature of 25o C, what is the net rate of heat transfer by radiation from the environment to a 15o C freshwater pond with a surface area of 20m2 ? The emissivity of water is 0.95.

1084 J/s

For the system below, what force does the 10 kg block apply to the 5 kg block? Neglect any effects due to friction.

10N

The sides of a small rectangular box are measured 1.80cm and 2.05cm long and 3.1cm high. Calculate its volume and uncertainty in cubic centimeters. Assume the measuring device is accurate to ±0.05cm.

11.4+-0.8cm3

How much work does she do if her center of mass rises 0.240 m?

118 J

A point charge moves from x = 5.0 m to x = 11 m in a 2.0 N/C electric field aligned with the x-direction. What change in voltage does the charge experience?

12 V

What force is exerted on the tooth in Figure 8 if the tension in the wire is 25.0 N? Note that the force applied to the tooth is smaller than the tension in the wire, but this is necessitated by practical considerations of how force can be applied in the mouth. Explicitly show how you follow steps in the Problem-Solving Strategy for Newton's laws of motion. Braces are used to apply forces to teeth to realign them. Shown in this figure are the tensions applied by the wire to the protruding tooth. The total force applied to the tooth by the wire,Fapp, points straight toward the back of the mouth.

12.7N

A cleaner pushes a 4.50-kg laundry cart in such a way that the net external force on it is 60.0 N. Calculate its acceleration.

13.3m/s^2

Pressure in the spinal fluid is measured as shown in the figure. If the pressure in the spinal fluid is 10.0 mm Hg: What is the reading of the water manometer in?

13.6m water

What force must be exerted to compress the spring?

133 N

What is the efficiency of a subject on a treadmill who puts out work at the rate of 100 W while consuming oxygen at the rate of 2.00 L/min? The average walking (5 km/h) output is 280 W with an oxygen consumption of 0.80 L/min.

14.3%

Working at this rate, how long will it take this person to lift 2000 kg of bricks 1.50 m to a platform? (Work done to lift his body can be omitted because it is not considered useful output here.)

141 sec

The swimmer shown in the figure exerts an average horizontal backward force of 80.0 N with his arm during each 1.80 m long stroke.What is his work output in each stroke?

144 J

The time it takes for a dragster to cross the finish line is unknown. The dragster accelerates uniformly from rest at a rate of 26.0m/s2 for a quarter mile (0.250miles). What is the final velocity of the dragster?

145m/s

What force should the woman in the figure exert on the floor with each hand to do a push-up? Assume that she moves up at a constant speed.

147 N downward

What is the speed of sound in fresh water at 20 degrees Celsius?

1480 m/s

What is the density of 18.0-karat gold that is a mixture of 18 parts gold (density 19.32g/cm3), 5 parts silver (density 10.49g/cm3), and 1 part copper (density 8.8g/cm3)? (These values are parts by mass, not volume.) Assume that this is a simple mixture having an average density equal to the weighted densities of its constituents.

15.8g/cm3

A 5kg watermelon is raised 3m by carrying it up the stairs to the second floor. If g is 10m/s2, what is the potential energy gain of the watermelon?

150J

What is the period of 60.0Hz electrical power?

16.7 ms

The triceps muscle at the back of her upper arm has an effective lever arm of 1.75 cm, and she exerts force on the floor at a horizontal distance of 20.0 cm from the elbow joint. Calculate the magnitude of the total force from both triceps muscles, and compare the total force of both triceps muscles to her weight.

1680 N, 3.4 times her weight

A cliff diver pushes off horizontally from a cliff and lands in the ocean 2.00s later. How fast was he going when he entered the water?

19.6m/s

How long will it take to increase the temperature of the 4.00-kg shoulder by 2.00º C, assuming no other heat transfer and given that its specific heat is 3.47×103 J/kg⋅ºC?

2 min 19 s

For the human body, what is the rate of heat transfer by conduction through the body's tissue with the following conditions: the tissue thickness is 3.00 cm, the change in temperature is 2.00ºC, and the skin area is 1.50m2. How does this compare with the average heat transfer rate to the body resulting from an energy intake of about 2400 kcal per day? (No exercise is included.)

2.00×101W, 17.2% of 2400 kcal per day

What is the period of a 1.00-m-long pendulum?

2.01 s

Calculate the magnitude of the electric field at the location of q, given that the square is 5.00 cm on a side.

2.04X10^7 N/C

A tightrope walker creates a tension of 588 N in a steel wire. Calculate how much this tension stretches the steel wire if the wire is originally 15.0 m long and 0.50 cm in diameter. (Young's modulus (Y) for steel is 210 × 109 N/m2)

2.1 mm.

During heavy lifting, a disk between spinal vertebrae is subjected to a 5000-N compressional force. What deformation is produced if the disk is 0.800 cm thick and has a Young's modulus of 1.5×109N/m2? Assume the disk has a uniform circular cross section of 2.00 cm in radius.

2.1X10-3cm

What deformation is produced if the disk is 0.800 cm thick and has a Young's modulus of 1.5×109N/m2?

2.1x10^-3cm

In practice the knees bend almost involuntarily to help extend the distance over which you stop. Calculate the average force produced if the stopping distance is 0.300 m.

2.35X10^3N

Concrete is pumped from a cement mixer to the place it is being laid, instead of being carried in wheelbarrows. The flow rate is 200 L/min through a 50.0-m-long, 8.00-cm-diameter hose, and the pressure at the pump is 8.00×106N/m2. Verify that the flow of concrete is laminar taking concrete's viscosity to be 48.0(N/m2)⋅s, and given its density is 2300 kg/m3.

2.54 << 2000, laminar.

On wet concrete, assuming that us=0.7

2.74m/s2

How high will water rise in a glass capillary tube with a 0.500-mm radius?

2.97 cm

An express train passes through a station. It enters with an initial velocity of 22.0m/s and decelerates at a rate of 0.150m/s2 as it passes through. The station is 210m long. How fast is the train going when the nose leaves the station?

20.5m/s

What is the average useful power output of a person who does 6.00×106J of useful work in 8.00 h?

208 W

An object accelerates according to the following acceleration versus time graph:If the object had an initial velocity of 12 m/s, what was the velocity of the object at t = 20 s?

20m/s

Recent studies have shown that spending time at a lower temperature can help increase weight loss through thermal uncoupling and shivering. Assuming a person spends 2hr per day for a week in temperatures cold enough to induce shivering, how much additional energy are they using? What can you infer about the effectiveness of this weight loss technique?

21.4 x 103 kJ - this would NOT be an effective weight loss method.

Assuming bicycle tires are perfectly flexible and support the weight of bicycle and rider by pressure alone, calculate the total area of the tires in contact with the ground. The bicycle plus rider has a mass of 80.0 kg, and the gauge pressure in the tires is 3.50×105Pa.

22.4cm2

Two children push on opposite sides of a door during play. Both push horizontally and perpendicular to the door. One child pushes with a force of 17.5 N at a distance of 0.600 m from the hinges, and the second child pushes at a distance of 0.450 m. What force must the second child exert to keep the door from moving? Assume friction is negligible.

23.3 N

Applying 12V across a resistor results in a current of 0.50A through the resistor. What is the resistance of the resistor?

24

Even when the head is held erect, as in the figure, its center of mass is not directly over the principal point of support (the atlanto-occipital joint). The muscles at the back of the neck should therefore exert a force to keep the head erect. That is why your head falls forward when you fall asleep in the class.

25 N downward

An object is sliding down an inclined plane at constant velocity. If the coefficient of kinetic friction between the object and the plane is 0.5, what is the angle of the plane?

26.57 degrees

A 63.0-kg sprinter starts a race with an acceleration of 4.20 m/s2. What is the net external force on him?

265 N

Blood is pumped from the heart at a rate of 5.0 L/min into the aorta (of radius 1.0 cm). Determine the speed of blood through the aorta.

27 cm/s

Calculate that object's net displacement over the time shown.

2790 m

What is 12.0∘C in kelvins?

285.2K

Calculate the power output of his arms if he does 120 strokes per minute.

288 W

Calculate the intensity of a wave if the power transferred is 10W and the area through which the wave is transferred is 5square meters.

2W/m2

Two waves undergo pure destructive interference. If the amplitude of one wave is 5m and that of the resultant wave is 3m, what is the amplitude of the second wave?

2m

If you are on a boat in the trough of a wave on the ocean, and the wave amplitude is 1m, what is the wave height from your position?

2m bc the height of a wave is two times the magnitude of its amplitude

Very large forces are produced in joints when a person jumps from some height to the ground. Calculate the average force produced if an 80.0-kg person jumps from a 0.600-m-high ledge and lands stiffly, compressing joint material 1.50 cm as a result. (Be certain to include the weight of the person.)

3.21X10^4 N

How much gravitational potential energy does the water gain?

3.39x10^-6 J

A person pushes a playground merry-go-round at its edge and perpendicular to its radius. He exerts a force of 85 N at the edge of the 30.0-kg merry-go-round. The merry-go-round has a 1.50 m radius. Consider the merry-go-round itself to be a uniform disk with negligible retarding friction. How long does it take the father to give the merry-go-round and child an angular velocity of 0.70 rad/s?

3.8 s

During heavy lifting, a disk between spinal vertebrae is subjected to a 5000-N compressional force. What pressure is created, assuming that the disk has a uniform circular cross section 2.00 cm in radius?

3.98x10^6 Pa

If she is standing barefoot on wet grass and has a resistance of only 4000 Ω.

30.0 mA, muscular contraction for duration of the shock

A person weighing 55kg walks by applying 160N of force on the ground, while pushing a 10kg object. If the person accelerates at 2m/s2, what is the force of friction experienced by the system consisting of the person and the object?

30N

Consider this figure of a disk rotating about an axis through the middle. The mass if the disk is 1.0kg. What is the net torque?

30Nm clockwise

An object accelerates according to the following acceleration versus time graph:If the object starts at the origin with an initial velocity of 12.0 m/s, what is the position of the object after 20.0 s?

320 m

A mysterious cube of unknown origin is sliding along a horizontal frictionless surface with a velocity of 17.7 m/s. An experimental energy beam is aimed at the cube. The beam decreases the velocity of the cube from 17.7 to 9.99 m/s. For unknown reasons the box has a mass of exactly π kg, that is 3.14159 kg. How much negative work did the experimental beam do on the mysterious cube?

335 J

What is the maximum resistance that can be obtained from a 10 Ω and a 25 Ω resistor?

35

A gymnast is attempting to perform splits. From the information given in the figure, calculate the magnitude and direction of the force exerted on each foot by the floor.

350 N directly upwards

What is the resistance in the circuit below if the voltage source is a 9.0 V battery and the current is 0.25 A?

36 Ω

An orchestra is practicing a piece that is to be played at an allegro tempo. The conductor sets a metronome at 160 beats per minute to keep everyone at the same pace. What is the period of a single beat?

375 ms

What is the rate of heat conduction through the 3.00-cm-thick fur of a large animal having a 1.40-m2 surface area? Assume that the animal's skin temperature is 32.0ºC, that the air temperature is -5.00ºC, and that fur has the same thermal conductivity as air.

39.7 W

Gamma radiation has a wavelength of 1.5×10−14m and a frequency of 2.0×1022Hz . Use these values to calculate the speed of light in a vacuum.

3x10^8 m/s

Assume the mostly infrared radiation from a heat lamp acts like a continuous wave with wavelength 1.50μm.If the lamp's 200-W output is focused on a person's shoulder, over a circular area 25.0 cm in diameter, what is the intensity in W/m2?

4.07kW/m2

Calculate the maximum acceleration of a car that is heading up a 4º slope (one that makes an angle of 4º with the horizontal) under the following road conditions. Assume that only half the weight of the car is supported by the two drive wheels and that the coefficient of static friction is involved—that is, the tires are not allowed to slip during the acceleration. (Ignore rolling.) On dry concrete, assuming that μs=1.0.

4.20m/s2

A particular sound, S1, has an intensity 3 times that of another sound, S2. What is the difference in sound intensity levels measured in decibels?

4.77dB

As blood passes through the capillary bed in an organ, the capillaries join to form venules (small veins). If the blood speed increases by a factor of 4.00 and the total cross-sectional area of the venules is 10.0cm2, what is the total cross-sectional area of the capillaries feeding these venules?

40.0 cm2

What is the volume of the bone?

41.4 cm3

Bird bones have air pockets in them to reduce their weight—this also gives them an average density significantly less than that of the bones of other animals. Suppose an ornithologist weighs a bird bone in air and in water and finds its mass is 45.0 g and its apparent mass when submerged is 3.60 g (the bone is watertight). What mass of water is displaced?

41.4 g

How much heat does it take to raise the temperature of 10.0kg of water by 1.0∘C?

42kJ

During forced exhalation, such as when blowing up a balloon, the diaphragm and chest muscles create a pressure of 60.0 mm Hg between the lungs and chest wall. What force in newtons does this pressure create on the 600 cm2 surface area of the diaphragm?

479 N

What is her useful power output if she does 25 pushups in one minute?

49 W

An object with a mass of 10kg rests on a plane inclined 60∘ from horizontal. What is the component of the weight force that is perpendicular to the incline?"

49.0N

A 65kg swimmer pushes off the pool wall and accelerates at 6m/s2. The friction experienced by the swimmer is 100N. What is the magnitude of the force that the swimmer applies on the wall?

490N

A farmer making grape juice fills a glass bottle to the brim and caps it tightly. The juice expands more than the glass when it warms up, in such a way that the volume increases by 0.2% (that is, ΔV/V0=2×10−3) relative to the space available. Calculate the force exerted by the juice per square centimeter if its bulk modulus is 1.8×109N/m2, assuming the bottle does not break. In view of your answer, do you think the bottle will survive?

4×102N/cm2. No

How big is the image of a 5.00 mm diameter mole?

5.00 cm

How many capillaries are involved if their average diameter is 10.0μm?

5.09x10^7

A small metal sphere with a net charge of 3.0nC is touched to a small second metal sphere that is initially neutral. The spheres are then placed 20cm apart. What is the force between the spheres?

5.1x10^-7 N

Aluminum has a specific heat of 900 J/°C. How much energy would it take to change the temperature of a sample of aluminum with a mass of 2.0 kg by 3 °C?

5.4kJ

A tree falls in a forest. How many years must pass before the 14C activity in 1.00 g of the tree's carbon drops to 1.00 decay per hour?

5.6x10^4y

Find the peak magnetic field strength.

5.84μT

What is the resistance of R1 in the circuit below?

50

An object weighs 294N on Earth. What is its weight on the Moon?

50.1 N

Archimedes' principle can be used to calculate the density of a fluid as well as that of a solid. Suppose a chunk of iron with a mass of 390.0 g in air is found to have an apparent mass of 350.5 g when completely submerged in an unknown liquid. What is the volume of iron, using its density as 7.8 cm3?

50cm3

How much water can be heated from 50 °F to 80 °F with 4.0 kJ of energy input?

57 g

A cyclist is traveling at 10m/s when he comes to a hill. He stops pedaling at the bottom of the hill and lets the bicycle coast up the hill. Assuming no energy is lost to friction and g equals 10m/s2 , what will be the vertical height of the bicycle when it stops coasting?

5m

A graph of velocity vs. time is shown for a world-class track sprinter in a 100-m race. Which of the following correctly gives his average velocity for the first 4 s and his instantaneous velocity at t = 5 s? a

6 m/s and 12 m/s

The action potential occurs when the voltage across a cell membrane experiences an increase from the resting potential (−70.mV) to about 30.mV. This depolarization, in turn, causes a similar response all along the cell membrane; the result is an electrical impulse that sends a signal along the axon of a neuron. The cell membranes can be about 5.0nm across and have an electric field across them due to the change in potential. What is the electric field across the membrane at the time of the action potential?

6.0x10^6 N/C

At its lowest point, a pendulum is moving at 7.77 m/s. What is its velocity in m/s after it has risen 1.00 m above the lowest point?

6.39 m/s

When an 80.0-kg man stands on a pogo stick, the spring is compressed 0.120 m. What is the force constant of the spring? Will the spring be compressed more when he hops down the road?

6.53x10^3 N/m Yes

A hockey puck with a mass of 160 g is sliding across an empty ice rink. The coefficient of friction between the hockey puck and the ice is 0.051. The puck travels 47.7 m before coasting to a stop. What was the initial velocity of the puck?

6.91 m/s

Following vigorous exercise, the body temperature of an 80.0-kg person is 40.0ºC. At what rate in watts must the person transfer thermal energy to reduce the the body temperature to 37.0ºC in 30.0 min, assuming the body continues to produce energy at the rate of 150 W? (1 watt = 1 joule/second or 1 W = 1 J/s).

617 W

Calculate the power output in watts and horsepower of a shot-putter who takes 1.20 s to accelerate the 7.27-kg shot from rest to 14.0 m/s, while raising it 0.800 m. (Do not include the power produced to accelerate his body.)

641 W, 0.860 hp

How many flights of stairs is this if each flight has 16 steps?

69 flights of stairs

Dogs can hear frequencies of up to 45kHz. What is the wavelength of a sound wave with this frequency traveling in air at 0∘C?

7.4 X 10-3 M

How many electrons pass through the wires connected to the patient?

7.50x10^17 electrons

What is the force exerted by the pivot on the head?

75 N upward

What is the reading if the person sits up, placing the top of the fluid 60 cm above the tap? The fluid density is 1.05 g/mL.

76.5 cm water

You sit in a car that is moving at an average speed of 86.4 km/h. During the 3.3 s that you glance out the window, how far has the car traveled?

79 m

An object rests on an inclined plane. If its mass is 25kg, and the parallel component of its weight is 35N, what angle does the inclined plane make with the horizontal?

8.21

Some fish have a density slightly less than that of water and must exert a force (swim) to stay submerged. What force must an 85.0-kg grouper exert to stay submerged in salt water if its body density is 1015kg/m3?

8.21 N

A small artery has a length of 1.1×10−3m and a radius of 2.5×10−5m. If the pressure drop across the artery is 1.3 kPa, what is the flow rate through the artery? (Assume that the temperature is 37º C.)

8.7x10^-11m3/s

What food intake will the animal need in one day to replace this heat transfer?

820 kcal

You are pumping up a bicycle tire with a hand pump, the piston of which has a 2.00-cm radius. What force in newtons must you exert to create a pressure of 6.90×105Pa ?

867N

Calculate the sound intensity level in decibels for a sound wave traveling in air at 0∘C and having a pressure amplitude of 0.656Pa.

87dB

Write the complete α decay equation for 226Ra. Find the energy released in the decay.

88226Ra138→86222Rn136+24He2; 4.87 MeV

calculate the force constant of its plunger's spring if you must compress it 0.150 m to drive the 0.0500-kg plunger to a top speed of 20.0 m/s.

889 N/m

What is the speed of a sound wave with frequency 2000Hz and wavelength 0.4m?

8x10^2 m/s

A bathroom scale that is calibrated to Earth's gravity shows your mass as 55kg. If you use the same scale on the moon, what mass will it show? (Hint: Remember that a scale measures the force of gravity. The acceleration due to gravity on the moon is 1.63 m/s2.)

9.1 kg

A 60.0-kg skier with an initial speed of 12.0 m/s coasts up a 2.50-m-high rise as shown in the figure. Find her final speed at the top, given that the coefficient of friction between her skis and the snow is 0.0800. (Hint: Find the distance traveled up the incline assuming a straight-line path as shown in the figure.)

9.46 m/s

How long can you rapidly climb stairs (116 steps/min) on the 93.0 kcal of energy in a 10.0-g pat of butter? The energy consumption rate is 685 W.

9.5 min

What is the magnitude of the acceleration due to gravity in a region where a simple pendulum with a length of 75.000cm has a period of 1.7357s?

9.8281 m/s2

Given a circuit with one 9V battery and with its negative terminal connected to ground. The two paths are connected to ground from the positive terminal: one path with a 20Ω and a 100Ω resistor and the second path with a 50Ω resistor. How much current will flow in the right branch?

9/120

A child slides down a playground slide. If the slide is 3m high and the child weighs 300N, how much potential energy does the child have at the top of the slide? (Round g to 10m/s2.)

900J

A diver on a diving board is undergoing simple harmonic motion. Her mass is 55.0 kg and the period of her motion is 0.800 s. The next diver is a male whose period of simple harmonic oscillation is 1.05 s. What is his mass if the mass of the board is negligible?

94.7 kg

How much tension is needed to lift an 888.0 kg elevator upward with an acceleration of 1.200 m/s2?

9768 N

Pascal's principle says:

A change in pressure at one point in an incompressible fluid is felt at every other point in the fluid.

A body with mass m is pushed along a horizontal surface by a force F and is opposed by a frictional force f. How would you draw a free-body diagram to represent this situation?

A dot with an arrow pointing right, labeled F, and an arrow pointing left labeled f that is of equal length or shorter than F

Why is a sound wave also called a compression wave?

A sound wave compresses and expands the molecules of the medium with every cycle.

Part A. When you stand in front of an open fire, you can sense light waves with your eyes. You sense another type of electromagnetic radiation as heat. What is this other type of radiation? Part B. How is this other type of radiation different front light waves?

A. infrared rays B. The infrared rays have lower frequencies and longer wavelengths than the light waves.

Suppose that the net external force (push minus friction) exerted on a lawn mower is 51N parallel to the ground.The mass of the mower is 240kg. What is its acceleration? What can you say about the external force acting on the system?

Acceleration is 0.21m/s2. The force exerted by the person pushing the mower must be greater than the friction opposing the motion

Describe electromagnetic force as explained by Maxwell's equations.

According to Maxwell's equations, electric force and magnetic force are different manifestations of electromagnetic force.

In a longitudinal sound wave, after a compression wave moves through a region, the density of molecules briefly decreases. Why is this?

After a compression wave, some molecules move forward temporarily.

What will be the change in velocity each second if acceleration is 10 m/s/s?

An acceleration of 10m/s/s means that every second, the velocity increases by 10m/s.

How are beats produced?

Beats are produced by the superposition of two waves with slightly different frequencies.

In a dental office, the person giving a dental x-ray examination leaves the room while the x-ray source is active. Dental office workers do not, however, take similar precautions against the bright lights of the exam room. Explain this difference.

Because x-ray photons carry much more energy than the photons of visible light, repeated exposure to x-rays can cause much more cumulative cell damage to the dental worker.

Why is decibel (dB) used to describe loudness of sound?

Because, the way our ears perceive sound can be more accurately described by the logarithm of the intensity of a sound rather than the intensity of a sound directly.

Suppose a blood vessel's radius is decreased to 90.0% of its original value by plaque deposits. How much does this reduce the blood flow assuming the body keeps the same pressure difference?

Blood flow is reduced by 34.3%.

Two similar boxes rest on a table. One is empty and the other is filled with pebbles. Without opening or lifting either, how can you tell which box is full? Why?

By applying an external force. Whichever box accelerates faster is lighter and so must be empty.

Water flows through this pipe. Where is the fluid's speed highest?

C

Identify which of the following actions generates more power. Show your work. carrying a 100N TV to the second floor in 50s or carrying a 24N watermelon to the second floor in 10s?

Carrying a 24N watermelon generates more power than carrying a 100N TV to the same height because power is defined as the ratio of work done and the time interval.

Radiotherapy is more likely to be used to treat cancer in elderly patients than in younger ones. Explain why.

Cells in the body of an elderly person are dividing at a slower rate than in a younger person.

Look at the drawing below of the electric field. What are the relative strengths and signs of the three charges?

Charge 1 is a positive charge, while charges 2 and 3 are negative. Charge 2 is weakest. The strengths of charges 1 and 3 are equal and stronger.

Which colors of the rainbow bend most when refracted?

Colors with a shorter wavelength and higher frequency bend most when refracted.

What is the unit of sound intensity level?

Decibles

A cyclist rides 3km west and then turns around and rides 2km east. What is her displacement? What distance does she ride? What is the magnitude of her displacement?

Displacement is −1km, distance is 5km, and the magnitude of displacement is 1km.

If you applied a voltage across two points A and B, how would you calculate the electric field between those points?

Divide the voltage by the distance between the points.

How is electric potential related to electric potential energy?

Electric potential is related to electric potential energy by the inverse of the unit charge at a given position in space.

A 75-kg man stands on his toes by exerting an upward force through the Achilles tendon, as in the figure. What is the force in the Achilles tendon if he stands on one foot

FA=2.21X103 upward

Calculate the force at the pivot of the simplified lever system shown—that force is representative of forces in the ankle joint.

FB=2.94X103 downward

Calculate the force on the joint

FJ=84.0 N downward

True or False: From a single magnet, it is not possible to make an odd number of magnets

False

Two people push a cart on a horizontal surface by applying horizontal forces F1 and F2 in the same direction. Which statement describes the magnitude of the net force acting on the cart, Fnet?

Fnet<F1+F2 because the net force will include frictional force.

Unlike most of the other muscles in our bodies, the masseter muscle in the jaw, as illustrated in the figure, is attached relatively far from the joint, enabling large forces to be exerted by the back teeth. Using the information in the figure, calculate the force exerted by the teeth on the bullet.

Fteeth on bullet = 1.2 X 102 N upward

Suppose a horse leans against a wall as in the figure. Calculate the force exerted on the wall assuming that force is horizontal while using the data in the schematic representation of the situation. Note that the force exerted on the wall is equal and opposite to the force exerted on the horse, keeping it in equilibrium. The total mass of the horse and rider is 500 kg. Take the data to be accurate to three digits.

Fwall=1.43x103N

Standing in front of a fire, we can sense both its heat and its light. Part A. Explain how the light and heat radiated by the fire are the same, and how they differ. Part B. Explain why we can't see and feel both the light and heat.

Heat and light are both forms of electromagnetic radiation, but light waves have higher frequencies.

Galileo's experiments proved that, contrary to popular belief, heavy objects do not fall faster than light objects. How do the equations you used support this fact?

Heavy objects do not fall faster than the light objects because while conserving the mechanical energy of the system, the mass term gets cancelled and the velocity is independent of the mass. In real life, the variation in the velocity of the different objects is observed because of the non-zero air resistance.

Design a temperature scale where the freezing point of water is 0 degrees and its boiling point is 70 degrees. What would be the room temperature on this scale?

If room temperature is 25.0∘C, the temperature on the new scale will be 17.5∘.

Why is no sound heard by the observer when an object approaches him at a speed faster than that of sound?

If the source exceeds the speed of sound, all the sound waves produced are behind the source. Hence, the observer hears the sound only after the source has passed.

What effect does increasing the internal resistance of the source have on the load circuit?

Increasing internal resistance reduces the current that can be drawn from the source.

You look at a graph of velocity versus time that forms a straight line with positive slope. What would it mean if you increased the slope but kept the y-intercept constant? What would it mean if you increased the y-intercept but kept the slope constant?

Increasing the slope would mean that the acceleration increased. Increasing the y-intercept would increase the velocity at t=0.

In the equation L=Iω, what is I?

Inertia

Consider the velocity vs. time graph shown below of a person in an elevator. Suppose the elevator is initially at rest. It then speeds up for 3seconds, maintains that velocity for 15seconds, then slows down for 5seconds until it stops. Find the instantaneous velocity at t=10s and t=23s.

Instantaneous velocity at t=10s and t=23s are 3m/s and 0m/s.

Explain how you can use the graph of position versus time shown below to describe the change in velocity over time. Identify (b) the time (ta,tb,tc,td or te) at which the instantaneous velocity is greatest, (c) the time at which it is zero, and (d) the time at which it is negative.

Instantaneous velocity is greatest at ta, zero at td and negative at te.

Heroes in movies hide beneath water and breathe through a hollow reed. In practice, water pressure would be pushing on your muscles. Make a claim based on breathing through a straw based on this information.

It is possible in shallow water. In deeper water, it would not be possible to inhale.

Two surfaces in contact are moving slowly past each other. As the relative speed between the two surfaces in contact increases, what happens to the magnitude of their coefficient of kinetic friction?

It remains constant and is independent of the relative motion.

If a pendulum from earth is taken to the moon, will its frequency increase or decrease? Why?

It will decrease because g on the Moon is less than g on Earth.

What is always true about an object with a velocity of zero?

Its displacement is zero.

If the amplitude of the displacement of a spring were larger, how would this affect the graph of displacement over time? What would happen to the graph if the period was longer?

Larger amplitude would result in taller peaks and troughs and a longer period would result in greater separation in time between peaks.

What is the difference between linear force and torque?

Linear force can cause motion in straight line whereas torque can cause rotational motion.

Look at the graph of velocity and time for an object. Over what intervals is the object experiencing positive and negative acceleration?

Look at the graph of velocity and time for an object. Over what intervals is the object experiencing positive and negative acceleration?

A skydiver steps out the hatch of a plane. Considering that air resistance will have a significant effect on the skydiver's motion, which graphs of his motion with respect to his starting point will have positive slopes? Magnitude of acceleration versus time. Magnitude of velocity versus time. Magnitude of displacement versus time.

Magnitude of velocity versus time and magnitude of displacement versus time.

Create a velocity vs. time graph based on the graph shown above. What is the net displacement as calculated from the velocity vs. time graph you just made, and how does it compare to the original graph?

Net displacement is −2m, and it is same as displacement shown in the position vs. time graph.

Is the speed of sound dependent on its frequency?

No

Does sound travel at the same speed in air and in water?

No, sound does not travel at the same speed in air and in water.

A participant in a winter sporting event pushes a 45 kg block of ice across an ice rink as shown in the figure. If this person is applying a force of 51 N, will they be able to move the object? (Take Earth's gravity as 9.8 m/s2; the coefficienct of static friction (µs) is 0.1 for ice on ice)

No, the angle causes the vertical component of the force to be added to the normal force, which would increase friction.

Do periodic waves require a medium to travel through?

No, the requirement of a medium for propagation does not depend on whether the waves are pulse waves or periodic waves.

If a force pushes a body to the east and another force of equal strength pushes it to the north, in what direction will the body move?

Northeast

What is the weight of a 5kg object on Earth and on the Moon?

On Earth the weight is 49N, and on the Moon the weight is 8.35N.

Why does it feel hotter on more humid days, even though there is no difference in temperature?

On hot, dry days, the evaporation of the sweat from the skin cools the body, whereas on humid days the concentration of water in the atmosphere is higher, which reduces the evaporation rate from the skin's surface.

Which part, (a) or (b), is represented when the velocity vector is on the positive side of the scale and the acceleration vector is set on the negative side of the scale? What does the car's motion look like for the given scenario?

Part (b). The car is slowing down because the acceleration and velocity vectors are acting in the opposite directions.

What power is dissipated by a 125 resistor with 12V applied across it?

Power dissipated by a resistor is 1.2W.

Given that (R1>R2>R3>R4), explain which resistor in the circuit below has the most current flowing through it.

R4

Why is radioactive iodine used to monitor the thyroid?

Radioactive iodine can be used by the thyroid while emitting information about the thyroid.

Compare both forces with the weight of the person. a

Ratio of net force to weight of person is 41.0 in part 1; 3.00 in part 2

Are rockets more efficient in Earth's atmosphere or in outer space? Why?

Rockets are more efficient in outer space than in Earth's atmosphere because the air in Earth's atmosphere does not provide thrust but does create more air friction than in outer space.

Why can light travel through outer space while sound cannot?

Sound waves are mechanical waves and require a medium to propagate. Light waves can travel through a vacuum.

How is a human able to hear sounds?

Sound waves cause the eardrum to vibrate. A complicated mechanism converts the vibrations to nerve impulses, which are perceived by the person as sound.

Two springs are attached to two hooks. Spring A has a greater force constant than spring B. Equal weights are suspended from both. Which of the following statements is true?

Spring B will have more extension than spring A.

Which of the following would make us feel colder: a) standing in air at 5∘C; b) standing in water at 5∘C ? Why?

Standing in water at 5∘C feels colder, because water is a better conductor of heat.

A short circuit in a 120-V appliance cord has a 0.500-Ω resistance. Calculate the temperature rise of the 2.00 g of surrounding materials, assuming their specific heat capacity is 0.200 cal/g⋅ºC and that it takes 0.0500 s for a circuit breaker to interrupt the current. Is this likely to be damaging?

Temperature increases 860º C. It is very likely to be damaging.

Two cars of mass 1000kg and 2000kg are traveling at velocities 20km/h and 60km/h, respectively. Which car will require more force to achieve an acceleration of 2m/s2?

The 2000kg car will require more force.

How can you tell that the Sun's energy reaches us through radiation?

The Sun's energy reaches the Earth through radiation, because it is the only way to transfer energy through the vacuum of space.

When one presses the accelerator on the car, what happens to the sound from the car engine? What happens to its intensity? Why?

The amplitude of the sound from the car engine increases when the accelerator is pressed and the sound becomes louder. Since intensity is proportional to amplitude squared, the intensity rises too.

Which property of the wave is related to its intensity? How?

The amplitude of the wave is related to the intensity of the sound. The larger-amplitude oscillations indicate greater pressure maxima and minima, and the pressure is higher in greater-intensity sound.

Which premises are unreasonable or inconsistent?

The assumed radius of the pump is too large

How does the balloon keep the plastic loop hovering?

The balloon and the loop are both negatively charged. This will help the balloon to keep the plastic loop hovering.

A 50 kg bicyclist starts his ride down the road with an acceleration of 1m/s2 in air with a density of 1.2 kg/m3. If his velocity at a given moment is 2m/s, how much force is he exerting? Assume the area of his body is 0.5m2.

The bicyclist is exerting 51 N of force.

High-voltage overhead electric lines are not covered by insulation, unlike wires that are used in electric circuitry in homes. Based on the equation that gives power as a function of voltage and current, why do birds that land on a single high-voltage line not get electrocuted?

The bird that touches the high-voltage line is at the same potential as the electric line.

A 2000kg car is sitting at rest in a parking lot. A bike and rider with a total mass of 60kg are travelling along a road at 10km/h. Which system has more inertia? Why?

The car has more inertia, as its mass is greater than the mass of the bike.

A typical older incandescent light bulb was 60W. Assuming that 120V is applied across the light bulb, what is the current through the light bulb?

The current through the light bulb is 0.50A.

In a sound wave, which parameter of the medium varies with every cycle?

The density of the medium varies with every cycle.

Why are different radiopharmaceuticals used to image different parts of the body?

The different radiopharmaceuticals travel to different parts of the body.

What is a magnetic field?

The directional lines present inside and outside the magnetic material that indicate the magnitude and direction of the magnetic force.

Look at the figure. Find the distance and displacement traveled from the starting point for each path to the tip of the arrow. Which path has the maximum distance?

The distance for Path A is 7 m, Path B is 5 m, Path C is 13 m, and Path D is 8 m. The net displacement for Path A is 7 m, Path B is -5 m, Path C is 9 m, and Path D is -4 m. Path C has maximum distance and it is equal to 12 meters.

Using the symmetry of the arrangement, determine the direction of the electric field at the center of the square in the figure, given that qa=qb=−1.00μC and qc=qd=+1.00μC.

The electric field at the center of the square will be straight up.

A positive charge is located at x=0. When a negative charge is placed at x=10cm, what happens to the electric field lines between the charges?

The electric field lines become denser between the charges.

In the left circuit of suppose the voltage rating of the battery is 12V, and the resistances are R1=1.0Ω,R2=6.0Ω, and R3=13Ω. (a) What is the equivalent resistance? (b) What is the current through the circuit?

The equivalent resistance is 20 and the current through the circuit is 0.60A.

What is the equivalent resistance of the resistors in the following circuit?

The equivalent resistance is 30

Two springs are attached to two hooks. When equal weights are suspended from each spring, both stretch the same amount. What can be assumed about the force constants of both?

The force constant is the same for both springs.

What physical characteristic of a system is its force constant related to?

The force constant k is related to the stiffness of a system: the larger the force constant, the stiffer the system.

A seagull is sitting in the water surface and a simple water wave passes under it. What sort of motion does the gull experience? Why?

The gull experiences mostly up-and-down motion but does not move in the direction of the wave.

A car is moving on a straight road at a constant speed in a single direction. Which of the following statements is true?

The magnitude of average velocity is equal to the average speed.

A person pushes a box from left to right and then lets the box slide freely across the floor. The box slows down as it slides across the floor. When the box is sliding freely, what is the direction of the net external force? Why?

The net external force acts from right to left.

Why do X-rays and gamma rays have equivalent RBE values if they provide different amounts of energy to the body?

The penetration distance, which depends on energy, is long for both X-rays and gamma rays.

As the angle of the incline gets larger, what happens to the magnitudes of the perpendicular and parallel components of gravitational force?

The perpendicular component will decrease and the parallel component will increase.

Break the velocity vs. time graph shown into sections and use them to construct a position vs. time graph. Describe the time interval at which the graph will have a negative slope.

The position vs. time curve will have a negative slope from 5 to 10 s.

Even without the number labels on the thermometer, you could tell which side is marked Fahrenheit and which is Celsius by how the degree marks are spaced. Why?

The separation between two consecutive divisions on the Fahrenheit scale is smaller than the similar separation on the Celsius scale, because each degree Celsius is equal to 1.8 degrees Fahrenheit.

Do you think that when you double the volume of a sound wave you are doubling the sound intensity level (in dB) or the sound intensity (in W/m2)? Why?

The sound intensity level in dB because it is a closer measure of how humans perceive sound.

Two simple harmonic oscillators are constructed by attaching similar objects to two different springs. The force constant of the spring on the left is 5N/m and that of the spring on the right is 4N/m. If the same force is applied to both, which of the following statements is true?

The spring on the left will oscillate faster than spring on the right.

Using the graph, what is the average velocity for the whole ten seconds?

The total average velocity is 1.2m/s.

Which two types of variables are included in Snell's law?

The two types of variables are refractive index of a material and the angle made by a light ray with the normal.

Calculate the wave velocity of the ocean wave in the figure above if the distance between wave crests is 10.0m and the time for a seagull to bob up and down is 5.00s.

The velocity of the ocean wave is 2.00m/s.

Did it take longer to heat the water or the sand/soil to the same temperature? Which sample took longer to cool? What does this experiment tell us about how the specific heat of water compared to the specific heat of land?

The water will take longer to heat as well as to cool. This tells us that the specific heat of water is greater than that of land.

What is unreasonable about this result?

This is too much force to exert with a hand pump.

When you focus a camera, you adjust the distance of the lens from the film. If the camera lens acts like a thin lens, why can it not be kept at a fixed distance from the film for both near and distant objects?

To focus on a distant object, you may need to increase or decrease the focal length of the lens.

The graph shows the motion of a shark through the water over the course of a day. What is the total distance that the shark travels throughout the day and what is its net displacement?

Total distance is 60 km, and the net displacement is 0 km.

True or False: A marble rolls down a slope from height h1and up another slope to height h2, where (h2<h1). The difference mg(h1−h2) is equal to the heat lost due to the friction.

True

True or False: Conservation of charge is like balancing a budget.

True

Three parallel plates are stacked above each other, with a separation between each plate. If the potential difference between the first two plates is ΔV1 and the potential between the second two plates is ΔV2, what is the potential difference between the first and the third plates?

V3=V2+V1

Which of the following correctly states at what time the shark's velocity is greatest and its velocity at that time?

Velocity is greatest between hours 2 and 3. Its velocity at that time is 30 km/hour.

What can you definitely say about the motion described in the graph?

Velocity is increasing.

Which expression represents power?

W/t

The figure below shows a schematic of a water molecule. Based on this image, explain, in terms of Coulomb's law why water molecules are attracted by both positive and negative charges.

Water molecules are polar

Compare how quickly the different materials are heated or cooled. Based on these results, what material do you think has the greatest specific heat? Why? Which has the smallest specific heat? Can you think of a real-world situation where you would want to use an object with large specific heat?

Water will take the longest, and iron will take the shortest time to heat, as well as to cool. Objects with greater specific heat would be desirable for insulation. For instance, woolen clothes with large specific heat would prevent heat loss from the body.

A hot piece of metal needs to be cooled. If you were to put the metal in ice or in cold water, such that the ice did not melt and the temperature of either changed by the same amount, which would reduce the metal's temperature more? Why?

Water would reduce the metal's temperature more, because water has a greater specific heat than ice.

When the surface is flat, you could say that one of the components of the gravitational force is zero; Which one? As the angle of the incline gets larger, what happens to the magnitudes of the perpendicular and parallel components of gravitational force?

When the angle is zero, the parallel component is zero and the perpendicular component is at a maximum. As the angle increases, the parallel component increases and the perpendicular component decreases. This is because the cosine of the angle shrinks while the sine of the angle increases.

A marble rolls up a slope, comes to a stop, and rolls back down. Assume the positive direction is up the slope. Which of the following is the best description of the marble's motion?

When the marble rolls down the slope, the marble is speeding up and the acceleration is in the negative direction.

A 5kg box is at rest on the floor. The coefficient of static friction between the box and the floor is 0.4. A horizontal force of 50N is applied to the box. Will it move?

Yes, because the applied force is more than the maximum limiting static friction.

A certain slide projector has a lens with a focal length of 100mm. (a) How far away is the screen, if a slide is placed 103mm from the lens and produces a sharp image? (b) If the slide is 2.40cm high, how high is the projected image? (Construct a ray diagram using paper, a pencil, and a ruler to confirm your calculations.)

a) 3.43m (b) -79.9cm

"Room temperature" is generally defined to be 25∘C. (a) What is room temperature in ∘F? (b) What is it in K?

a) 77∘F, (b) 298 K

What is the SI unit for electric current

ampere

For an object in simple harmonic motion, when does the maximum speed occur?

at the equilibrium position

The graph shows the motion of a shark through the water over the course of a day. Which of the following correctly provides the shark's average velocity and average speed for the whole day?

average velocity = 0 km/h, average speed = 8.6 km/h

Consider two identical oscillators made by attaching objects of the same mass to similar springs. The first oscillator is given a greater initial force in order to start the oscillations. The second is given a relatively smaller push. Which oscillator will oscillate faster?

both will oscillate at the same frequency

Define electric current in terms of other SI units.

coulombs per second

What is the term used for changes in shape due to the application of force?

deformation

An initial force F1 is applied to a ball. The ball then rolls away along the floor west to east. A frictional force, f, opposes the motion of the ball. What is the magnitude and direction of the additional force that should be applied to the ball to keep it moving at the same velocity?

f in the direction from west to east

A car has two horns, one emitting a frequency of 199 Hz and the other emitting a frequency of 203 Hz. What beat frequency do they produce?

f=4.00Hz

Suppose you take a magnifying glass out on a sunny day. You find that it concentrates sunlight to a small spot 8.00cm away from the lens. What are the focal length and power of the lens?

focal length =8.00cm, power=12.5D

What is the restoring force?

force which brings an object back to its equilibrium position

Which form of EM radiation has the most penetrating ability?

gamma rays

Which type of EM radiation has the shortest wavelengths?

gamma rays

Give an example of convection found in nature.

heat transfer through ocean currents

Which of the following terms is a useful quantity to describe the loudness of a sound?

intensity

Consider this circuit. If one of the 2 Ω resistors is removed, what happens to the voltage across the remaining resistor?

it is the same

What is another name for Newton's First Law?

law of inertia

A man holds a horizontal shovel full of snow; his right hand grasps the end of the shovel, with a force directed downward, while his left hand is located 45.0 cm away with a force directed upward (supporting the shovel); snow with mass 12.0 kg rests on the other end of the shovel. Assume the shovel is massless. The shovel is 1.60 m long. What force is exerted on the shovel by each hand?

left hand 418 N, right hand 301 N

Give an example of a wave that can propagate through a vacuum.

light wave

In the equation τ=rFsin⁡θ, what is F?

linear force

Which phase of water has the largest specific heat?

liquid

Which of these is not a characteristic of a wave?

mass

For a given oscillator, what are the factors that affect its period and frequency? .

mass and force constant

An isolated system contains two objects with charges q1 and q2. If object 1 loses half of its charge, what is the final charge on object 2?

q2+q1/2

How is energy transferred in a vacuum?

radiation

In the specific heat equation what does c stand for?

specific heat

What does c represent in the equation n=c/v?

speed of light in a vacuum

Which equation would you use to calculate your travel time on a straight road at constant speed if you used only mile markers and your speedometer?

t=d/vavg

A skier with a mass of 62kg is skiing down a snowy slope at an angle of 25∘. Find the coefficient of kinetic friction, μk, for the skier if friction is known to be 45.0N.

uk=0.08

A coin is sliding down an inclined plane at constant velocity. If the angle of the plane is 10∘ to the horizontal, what is the coefficient of kinetic friction?

uk=0.18

A person applies a force of 200N to move an object initially at rest weighing 400N. What could be the coefficient of static friction between the object and the surface?

us<0.5

When does the amplitude of an oscillating system become maximum?

when the frequency of the oscillator equals the natural frequency of the oscillating system

What is the equilibrium position of a pendulum?

when the pendulum is hanging straight down

Does a bat make use of the properties of sound waves to locate its prey?

yes

Will a sound wave with wavelength 5.0m and speed 360m/s be audible to humans?

yes

A person working at a drafting board may hold her head as shown in the figure, requiring muscle action to support the head. The three major acting forces are shown. Calculate the direction and magnitude of the force supplied by the upper vertebrae FV to hold the head stationary, assuming that this force acts along a line through the center of mass as do the weight and muscle force.

ºFV=97N,θ=59º