PHYS 221 Final exam study guide clickers
Compare the flight of two golf balls given the same impulse by the club. Which ball will travel a larger distance?
The dimple ball
The position of a mass on a spring as a function of time is shown below. Consider the time corresponding to point P. At this time the mass
positive velocity and negative acceleration.
Your dryer is broken, so you have to hang your wet clothes from the washing machine outside to dry. Under which conditions would your clothes dry fastest?
When it is 75°F with 50% relative humidity.
Substance A has a density of 2.0 g/cm3 and substance B has a density of 3.0 g/cm3 . In order to obtain equal masses of these two substances, the ratio VA /VB of the volume of A to the volume of B has to be equal to
3:2
A ball (mass 0.40 kg) is initially moving to the left at 40 m/s. After hitting the wall, the ball is moving to the right at 40 m/s. What is the impulse of the ball receives during its collision with the wall?
32 kg m/s to the right
Two blocks, one sitting on a table and the other heavier one hanging over its edge, are connected by a light string as shown in the figure. Which force makes the block on the table move, the tension in the string or the weight of the hanging block?
the tension
If the intensity of a 40 dB sound is increased to 80 dB, the intensity in W/m2 increases by a factor of
10^4
A wave travelling in the +x direction is described by the equation y = 0.1 sin (10 x − 100 t), where x and y are in meters and t is in seconds. Calculate (i) the wavelength, (ii) the period, (iii) the speed, and (iv) the amplitude of the wave
(i) 0.63 m, (ii) 0.063 s, (iii) 10 m/s, (iv) 0.1 m
A wave travelling in the +x direction is described by the equation y = 10 m sin (5 x − 20 t) where x and y are in meters and t is in seconds. Calculate (i) the wavelength, (ii) the period, (iii) the speed, and (iv) the amplitude of the wave.
(i) 1.26 m, (ii) 0.314 s, (iii) 4 m/s, (iv) 10 m
Organ pipe B is open at both ends and is half as long as organ pipe A, which is open at one end, as shown. What is (i) the ratio of their fundamental wavelengths λA : λB and (ii) the ratio of their fundamental frequencies fA : fB ?
(i) 4:1 (ii) 1:4
Which of the following wave functions describe a wave that moves in the -x-direction? 1. y(x,t) = A sin (-kx - ωt) 2. y(x,t) = A sin (kx + ωt) 3. y(x,t) = A cos (kx + ωt)
1, 2, and 3
A pure sound notes from a sources make the molecules of air at a location vibrate simple harmonically in accordance with the equation y1 = 0.008 sin (302 π t). What is the frequency of the sound wave?
151 Hz
A sample of water at 0 oC is slowly converted into ice at 0 oC? The entropy of the sample changes by ΔS = -0.586 kcal/K. What is the mass of the sample? The latent heat of fusion is 80 kcal/kg.
2 kg
A force of magnitude 10 N compresses an ideal spring by 4 mm. How much force is needed to stretch the same spring by 12 mm?
30 N
5 moles of a monatomic gas has its pressure increased from 105 Pa to 3*105 Pa. This process occurs at a constant volume of 0.1 m3 . Determine the change in the internal energy of the gas
30000 J
A pure sound notes from a sources make the molecules of air at a location vibrate with simple harmonic motion in accordance with the equation y1 = 0.008 sin (604 π t). What is the frequency of the sound wave?
302 Hz
A piece of clay with mass m = 0.01 kg collides with the floor at speed of 8 m/s and sticks. The collision takes 0.02 s. The magnitude of the average force the piece of clay experiences during the collision is
4 N
A string of length 100 cm is held fixed at both ends and vibrates in a standing wave pattern. The first harmonic is shown. The wavelengths of the standing waves making up the pattern cannot be
400 cm
A rock is kicked horizontally at 10 m/s off a cliff. The rock strikes the ground 30 m from the cliff as shown in the figure. What is the approximate height of the cliff H?
45 m
A 300 kg roller coaster cart starts from rest at a point 45 m above the bottom of a dip. Neglect friction. What will be its kinetic energy at the top of the next hill, which is 30 m above the bottom of the dip? Let g = 10 m/s2 .
45000 J
When a tuning fork is sounded together with a 492 Hz tone, a beat frequency of 2 Hz is heard. Then a small piece of putty is struck to the tuning fork, and the tuning fork is again sounded along with the 492 Hz tone. The beat frequency decreases. What is the frequency of the tuning fork?
494 Hz
We flip a fair coin 10 times. Define a macrostate to be the number of heads. Which macrostate is most likely to occur?
5 heads
A ball is dropped from the top of a 125 m tall tower. How long after it has been released does it hit the ground? Let g = 10 m/s2 .
5 s
A block of wood of uniform density floats so that exactly half of its volume is underwater. What is the density of the block?
500 kg/m3
A non-constant force is applied to a 40 kg object over a distance of 20 m. (See diagram.) How much work does the force do?
80 J
The brake system in most cars makes use of a hydraulic system. This system consists of a fluid filled tube connected at each end to a piston. Assume that the piston attached to the brake pedal has a cross sectional area of one half a square inch and the piston attached to the brake pad has a cross section area of two square inches. When you apply a force of 20 pounds to the piston attached to the brake pedal, the force at the brake pad will be
80 pounds
Heat is added at a rate of 10.0 kJ/min to a 0.5 kg solid sample starting at t = 0 min. A temperature versus time diagram is shown. In which region(s) is the liquid phase present?
B and C
Consider a rod of uniform density with an axis of rotation through its center and an identical rod with the axis of rotation through one end. Which has the larger moment of inertia about its axis of rotation?
IC < IE
A fast pulsed laser emits a series of brief ps (10^-12 s) pulses of light, one pulse per microsecond (10^-6 s). If the energy per pulse is 5*10^-5 J, what is the power of a pulse?
5*10^7 W
A train whistle is blown by the driver who hears the sound at 600 Hz. If the train is heading towards a station at 25.0 m/s, what will the whistle sound like to a waiting commuter? Take the speed of sound to be 340 m/s.
647 Hz
A steel bridge is built in several segments, each 20 m long. The gap between segments is 2 cm at 18 oC. What is the maximum temperature that the bridge can manage before buckling?
95 oC
Consider three drinking glasses. All three have the same area base, and all three are filled to the same depth with water. Glass A is wider at the top than at the bottom, glass B is cylindrical and so holds less water than A. Glass C is narrower at the top than at the bottom, and so holds less water than B. Which glass has the greatest liquid pressure at the bottom?
All three have equal pressure at the bottom.
A horizontal external force of 10 N acts on a 4 kg box that slides across a surface with constant velocity. What is the coefficient of kinetic friction μk between the box and the surface? (Let g = 10 m/s2 .)
0.25
Suppose the earth's polar ice caps melted, sending water towards the equator and increasing the moment of inertia of the earth to 1.1 times its present value. The angular velocity of the earth would be
0.909 times its present value.
An ideal spring has a spring constant of 400 N/m. It is compressed by 0.1 m. How much work must an external force do to further compress the spring from 0.1 m to 0.13 m?
1.38 J
Two particles of masses 2 g and 6 g are separated by a distance of 6 cm. The distance of their center of mass from the heavier particle is
1.5 cm
A ball is thrown horizontally from the top of a 125 m tall tower with a speed of 20 m/s. What is its horizontal distance from the building when it strikes the ground? Let g = 10 m/s2 .
100 m
A block of wood of uniform density floats so that exactly ¼ of its volume is underwater. What is the density of the block?
250 kg/m^3
A car accelerates down a straight highway. Which of the free-body diagrams shown best represents this situation?
3
Two dice are thrown. Let the macrostate be the sum of the two numbers on the top faces. What is the multiplicity of the macrostate "4"?
3
A disk is spinning with angular velocity ω as shown. It begins to slow down. While it is slowing, what are the (i) directions of its angular velocity ω (ii) and its angular acceleration α?
C,D
Referring to the graph below, which phase has the smallest specific heat capacity?
gas
Consider a block of wood floating on water. If you push down on the top of the block until it is completely submerged, the buoyant force on it
increases
An ice-cube sits in a bath of water. The water, the ice and the surrounding air are all at 0 oC. Does heat enter the ice cube?
no
When a car is at rest, its horn emits a sound wave of wavelength 0.55 m. A person standing in the middle of the street hears the horn with a frequency of 560 Hz. If the speed of sound is 330 m/s, should the person jump out of the way?
no
A refrigerator
removes heat from a cold region and delivers more heat to a hotter region.
Consider a car at rest. We can conclude that the downward gravitational force Earth exerts on the car and the upward contact force the surface of Earth exerts on the car are equal in magnitude and opposite in direction because
the net force on the car is zero
Both the disk and the ring have the same mass, and the same radius. Which has the larger moment of inertia I about the center?
the ring
Standing waves are produced by periodic waves of
the same frequency, amplitude, and wavelength traveling in opposite directions.
It is possible for heat to flow across vacuum.
true
It is possible to change the temperature of a system when the system is insulated from its surroundings, so that no heat can flow into and out of the system.
true
If you double the wavelength λ of a wave on a string under fixed tension, what happens to the wave speed v and the wave frequency f?
v is unchanged and f is halved
Consider two specimens of ideal gas at the same temperature. The molecules in specimen #1 have greater molar mass than the molecules in specimen #2. How do the root-mean-square or RMS speeds, vrms = √, of molecules and the average translational kinetic energy per molecule, = ½m, compare in the two specimens?
vrms is greater in specimen #2; is the same in both specimens.
Heat is the transfer of disordered energy from one system to another. Is it possible for heat to enter a system while the temperature of the system does not change?
yes
By how much does the entropy of 100 g of water at 0 oC change if the water is slowly converted into ice at 0 oC? The latent heat of fusion is 80 kcal/kg.
-0.029 kcal/K
A simple pendulum of length L oscillates back and forth 10 times per second. By what factor do you have to change its length to make it oscillate back and forth only 5 times per second?
Increase the length by a factor of 4.
A chair has a wooden seat but metal legs. The chair legs feel colder to the touch than does the seat. Why?
The metal has a higher thermal conductivity than the wood.
Two bubbles are connected by a hollow tube plus a valve. What will happen once the valve between the two is opened?
The small bubble will drain into the big bubble.
Suppose you are on a cart, initially at rest on a frictionless, horizontal track. You throw a series of identical balls against a wall that is rigidly mounted to the cart. If the balls are thrown at a steady rate and bounce straight back, is the cart put into motion?
Yes, it starts to move to the left keeps on gaining speed.
Suppose you work in the E.R. and a choking patient comes in with their trachea half obstructed. (The diameter is half of what it was before the obstruction.) You manage to correct the problem and send them on their way safely, explaining that such obstructions are particularly dangerous because
a half - blocked airway passes only 1/16 the regular amount of air.
As a sound source moving with constant velocity approaches and then moves past a stationary observer, the observer will hear
a sudden drop in pitch.
People fighting forest fires carry emergency tents that have shiny aluminum outer surfaces. If there is trouble, a fire fighter can lie under the tent to block the heat from burning trees overhead. The tent helps because
radiation carries heat downward toward the fire fighter and the aluminum tent reflects most of that radiation.
Three identical wheels are all spinning with the same angular velocity ω. The total angular momentum of the 3-wheel system has magnitude L. One of the three wheels is flipped upside-down, while the magnitude of its angular velocity remains constant. What is the magnitude of the new angular momentum of the 3-wheel system ?
(1/3) L
Suppose you are standing on a bathroom scale while riding in an elevator. For a moment the scale reads 160 lb = 712 N while your actual weight is 180 lb = 800 N. What is your (and the elevator's) acceleration? (Let g = 10 m/s^2 .)
-1.1 m/s^2
A ball initially at rest is hit by a club. It is in contact with a club for 6.0*10^-3 seconds. Just after the club loses contact with the ball, the ball's velocity is 2.0 m/s. If the ball's mass is 50 g, what is the magnitude of the impulse the club gives to the ball?
0.1 kg m/s
A boy has a mass of 20 kg. He is standing on an icy pond, when a "friend" throws a 2 kg ball at him with horizontal velocity of 8 m/s. If the boy catches the ball, how fast will he be moving?
0.727 m/s
Angular speed is measured in units of s^-1 , which is rad/s. How many degrees correspond to 1 radian?
1 rad = 57.3 degrees
This pocket watch is keeping perfect time. What is the angular speed ω of its minute hand in units of rad/s?
1.75*10-3 rad/s
A gardener is watering her garden from a hose. With the water pressure full blast holding the hose horizontally she can just reach a distance of 12 m, but needs to water an area up to 15 m away. By what fraction must she reduce the cross-sectional area of the hose, still keeping the hose horizontal, to be able to water this area?
1/5
A 500 N weight sits on the small piston of a hydraulic machine in equilibrium. The small piston has area 2.0 cm2 . If the large piston has area 40 cm2 , how much weight does the large piston support ?
10000 N
A crane lifts a 100 kg object to a height of 10 m in 5 s. What is its power output?
1960 W
A fan rotating with an initial angular velocity of 1000 rev/min is switched off. In 2 seconds, the angular velocity decreases to 200 rev/min. Assuming the angular acceleration is constant, how many revolutions does the blade undergo during this time?
20
When a tube of diameter d is placed in water, the water rises to a height h. If the diameter were half as great, how high would the water rise?
2h
Mercury has an unusually large surface tension γ = 0.465 N/m. Calculate the excess pressure inside a drop of mercury 5 mm in diameter.
372 Pa
A junior lifter lifts his 80 kg weight bar three times straight up off the ground a distance of 1.6 m before releasing it. How much work does he do?
3763 J
Ice initially at -20 oC is to be turned into steam at 130 oC. To figure out how much heat is required, how many separate terms will there be (i.e. ΔQ = c*m*ΔT, ΔQ = m*LV , and ΔQ = m*Lf )?
5
Arnie and Wimpy are playing tug-of-war. They have the same weight, but Arnie wins, pulling Wimpy into the mud puddle. Why did Arnie win?
Arnie exerted a greater magnitude force on the ground than Wimpy exerted on the ground.
In the figure, a 100 N weight is suspended from two spring scales, each of which has negligible weight. What is the reading of the scales?
Each scale will read 100 N.
Why are good thermal conductors generally good electric conductors also?
Electron motion is responsible for determining both properties
A woman exerts a constant horizontal force pulling a box across a rough floor at a constant speed. What can you say about the work done by friction?
Friction does negative work
Orange growers in Florida spray their trees with water when they expect a freeze. Why does this work?
If a mixed phase of water and ice is present, the temperature does not drop below 0 oC.
Two blocks, one sitting on a table and the other heavier one hanging over its edge, are connected by a light string as shown in the figure. What is the acceleration of the blocks? The blocks accelerate together, the acceleration a is the same for both blocks. (1) m1 g - T = m1 a (2) T = m2 a
Insert (2) into (1). m1 g - m2 a = m1 a Solve for a. a = m1 g/(m1+m2 )
Consider the earth spinning from west to east on its axis. It is slowing down in its rotation due to friction with the air. Using the right hand rule, in what direction is the frictional torque?
N pole to S pole
Two objects have masses m1 and m2 , respectively. If m2 = 4m1 , and both have the same kinetic energy, which has more momentum (magnitude)?
Object 2 with mass m2 .
In the constellation Orion, you can easily observe the difference between the reddish looking star Betelgeuse and the bluish looking star Rigel. Which of the two has the hotter surface temperature?
Rigel
On a humid summer day, perspiration does not cool you off much. Why?
The air is almost saturated with water vapor and there is almost no net evaporation.
Suppose you work in the E.R. and a choking patient comes in with their trachea obstructed. The diameter is 1/3 of what it was before the obstruction. You manage to correct the problem and send them on their way safely, explaining that such obstructions are particularly dangerous because
The blocked airway passes only 1/81 the regular amount of air
A force of 20 N in the positive x-direction accelerates an object with acceleration a = 2 m/s^2 . When the object is moving with velocity v = 10 m/s, an additional force of 10 N in the negative x-direction is applied. Which statement is true?
The object now accelerates with acceleration a = 1 m/s^2 in the positive x-direction.
Blood flows through a section of a horizontal artery that is partially blocked by a deposit along the artery wall. A hemoglobin molecule moves from the wider region into the narrower region. What happens to the pressure acting on the molecule as it moves from the wider into the narrower region?
The pressure decreases.
The diagram below depicts two pucks on a frictionless table. Puck II is four times as massive as puck I. Starting from rest, the pucks are pushed across the table from the start to the finish line by two equal forces. Which puck will have the greater kinetic energy upon reaching the finish line?
They both have the same kinetic energy.
A pocket watch and Big Ben are both keeping perfect time. Which minute hand has the larger angular speed ω?
They both have the same ω.
Why can't you get all the dust off your car by just squirting water from a hose onto it? Why can't you simply remove dust just by blowing across a surface? Why does dust cling to a fast rotating fan? How can a leaf stay on a car moving at high speed?
This is a consequence of the formation of stationary boundary layer.
A heavy box sits in the back of a pickup truck. The truck and the box are accelerating towards the left. What is the direction of the frictional force on the box?
Towards the left
Water with air bubbles flows through a pipe that becomes narrower. Compared to the wider region, the bubbles in the narrow region are
bigger
In an experiment water rose by capillary attraction through two columns of soils, one with coarse grains (column 1) and the other with fine gains (column 2). In which column did the water rise to greater height?
column 2
When water flows smoothly in a straight hose, its viscosity causes the water to
convert some of its kinetic energy into thermal energy.
Two fluids have the same contact angle with glass. The density of fluid 1 is 1.2 times the density of fluid 2. (ρ1 = 1.2 ρ2 ) The surface tension of fluid 1 is twice that of fluid 2. (γ1 = 2γ2 ) Find the ratio h1 /h2 of the heights to which a liquid will rise through capillary action in the same capillary tube.
h1 /h2 = 1.67
A woman exerts a constant horizontal force on a large box. As a result, the box moves across a horizontal floor at a constant speed v0 . The constant horizontal force supplied by the woman
has the same magnitude as the total force which resists the motion of the box.
Some children are riding on the outside edge of a merry-go-round. Ignore friction in the rotation of the merry-go-round. Consider the "system" of the children plus the merry-go-round. At the same time, the children all move towards the center of the merry-go-round. When they do this
the angular momentum of the system stays constant.
Your hands push on a heavy box to slide it across the floor. The other force of the action/reaction pair is
the box pushing backward against your hands.
As I apply the brakes in my car, books on the passenger seat suddenly fly forward. That is most likely because
the decelerating car is not an inertial reference frame.
A baseball bat with uniform density is cut at the location of its center of mass as shown in the figure. The piece with the smaller mass after the cut is
the piece on the left
Two objects with different masses collide and stick to each other. Compared to before the collision, the system of two objects after the collision has
the same total momentum but less total kinetic energy
A string is clamped at both ends and plucked so it vibrates in a standing wave between two extreme positions as shown by the dashed lines below. If the string has length L and the frequency of oscillation of this mode is f, the speed of the waves on that string is
(2/3)fL
A 65 kg physics student is at rest on a 5 kg sled that also holds a chunk of ice with a mass of 2 kg. The student throws the ice horizontally with a speed of 10 m/s relative to the ground. If the sled slides over a frozen pond without friction, how fast (in m/s) are the sled and student traveling with respect to the ground after throwing the chunk of ice?
0.286 m/s
When the body requires an increased blood flow rate in a particular organ or muscle, it can accomplish this by increasing the diameter of arterioles on that area. By what factor must the diameter of an arteriole increase to double the volume flow rate of blood, all other factors remaining the same?
1.19
Two particles of masses 2 g and 8 g are separated by a distance of 6 cm. The distance of their center of mass from the heavier particle is
1.2 cm
How much negative pressure, with respect to atmospheric pressure, do your lungs have to produce, so you can you suck water through a straw to a height of 12 cm?
1.2 kPa
A car has a maximum acceleration of 4.5 m/s^2 . What would be its maximum acceleration while towing a second car twice its mass?
1.5 m/s^2
100 dB corresponds to what intensity, in W/m^2?
10^-2 W/m^2
Assume that a naked human body has a surface area of 1.5 m2 and a surface temperature of 32oC. If the surroundings are at a temperature of 16oC, calculate the net rate of heat loss by the body due to radiation. Assume an emissivity of 1.
143 W
A ball initially at rest is hit by a club. It is in contact with a club for 6.0*10^-3 seconds. Just after the club loses contact with the ball, the ball's velocity is 2.0 m/s. If the ball's mass is 50 g, what was the magnitude of the average net force acting on the ball while in contact with the club?
16.7 N
A ring shaped space station with a radius of 2 km is spinning, so that the speed of the rim is 100 m/s. A 50 kg woman sits on the inside of the rim. What is the magnitude of his apparent weight?
250 N
A fast pulsed laser emits a series of brief ps (10^-12 s) pulses of light, one pulse per microsecond (10^-6 s). If the average power of the laser is 50 W, what is the energy per pulse?
5*10^-5 J
Which sounds travel the fastest through air?
All sound travels at the same speed through air.
If ∆ = 1 m and the speed of sound is 340 m/s, which statement is correct?
At the frequency f = 680 Hz the sound at the position of the listener is loud. 2. At the frequency f = 1190 Hz the sound at the position of the listener is very soft. 3. At the frequency f = 340 Hz the sound at the position of the listener is loud.
Two objects, A and B, have the same volume and are completely submerged in a liquid, although A is deeper than B. Which object, if either, experiences the greater buoyant force?
Both objects experience the same buoyant force.
You have heard the tried and true phrase "it is like running in to a brick wall". Now it is time to dig a little deeper and modify the phrase. Assume you are in a car driving and come in contact with this proverbial brick wall. Your car can do three things after the strike: it can go through, come to stop or bounce back. Select the option which will be the most dangerous to you assuming similar collision times.
Bouncing back.
Two flutists are tuning up. If the conductor hears the beat frequency increasing, are the two flute frequencies getting closer together or father apart?
Farther apart
A metal body of mass 31.6 g occupies a volume of 4 cm^3 . Identify the metal.
Iron with density = 7.9 g/cm^3
Consider the change a gas undergoes as it transitions from point c to point a in the PV diagram. What type of process is this?
Isobaric
A young girl wishes to select one of the frictionless playground slides illustrated above to give her the greatest possible speed when she reaches the bottom of the slide. Which of the slides illustrated in the diagram should she choose?
It does not matter, her speed would be the same for each
When you fly a kite, there is a time when you must do positive work on the kite.
It is the time when you pull the kite in.
A gas, confined to an insulated cylinder, is compressed adiabatically (and reversibly) to half its original volume. Does the entropy of the gas increase, decrease, or remain unchanged during this process?
It remains unchanged.
Your friend asks you to stand perfectly still holding up a weight bar with weights while he takes a picture. Are you doing work during this time?
No
A 50 N force and a 100 N force both act on the same object. What is the net force (total force) acting on the object?
Not enough information is given
In your dorm room you watch the Vols play in an out-of-town game. It is a cliffhanger and the winner will be determined in the last few seconds of play. Everybody is taking their bathroom break right after the game ends. As the toilets flush and hands are washed, the faucet pressure is noticeably reduced, even though the supply pipe to the rooms can carry all the water needed. Why?
The water has to speed up in the supply pipe and therefore the pressure drops in the pipe.
How will the wavelengths of the harmonics of an open tube compare with those of a string of the same length L?
They will be the same.
An ice cube is placed in a cup containing some liquid water. The water and ice exchange energy with each other but not with the outside world. Consider the following possibility: After awhile, we find that the water has increased in temperature and ice has gotten colder. Which statement is correct?
This process can satisfy the 1st law, but still does not happen in nature
Why does heat, of itself, not flow from a cold to a hot object, if it is allowed by Newton's laws?
This would require a large departure from equilibrium, which is extremely unlikely
A rock is thrown from the roof of a tall building. While it is falling towards the ground, the force of gravity acting on it is
equal to its weight.
Suppose you are standing on a bathroom scale when you are flying in a jet airplane. For a moment the scale reads more than your actual weight. During that moment, the scale is exerting an upward force on you that is
greater than your weight.
When the kinetic energy of a moving object increases by a factor of 16, the magnitude of its momentum
increases by a factor of 4.
The _______ the temperature difference between hot and cold, the larger the fraction of heat you can divert and transform into __________.
larger; work
Is it possible to cool down a well insulated room on a hot summer day by leaving the refrigerator door open, and using the refrigerator as an air conditioner?
no
A simple pendulum consists of a point mass m suspended by a massless, unstretchable string of length L. If the mass is doubled while the length of the string remains the same, the period of the pendulum
remains unchanged.
When you sit facing a campfire outdoors, your face feels quite warm because
the campfire is radiating heat towards your skin.
Assume a disk and a ring with the same radius roll down an incline of height h and angle theta. If they both start from rest at t = 0, which one will reach the bottom first?
the disk
A car traveling at 100 km/hr strikes an unfortunate bug and splatters it. The magnitude of the force of impact is
the same for both.
A pitcher contains 0.50 kg of liquid water and 0.50 kg of ice at 0°C. You let heat flow into the pitcher until there is 0.75 kg of liquid water and 0.25 kg of ice. During this process
the temperature of the ice-water mixture remains the same.
Some engineers have suggested that we can simulate gravity in outer space by having a circular rotating space station where persons feel an outward-directed fictitious force due to the rotation of the station. The reason they feel such a force is because
they are accelerating toward the center of the space station and the walls of the space station provide the centripetal force, which they experience as an apparent weight.
Two balls of putty of equal mass approach each other from opposite directions with equal speeds. They stick together and come to rest. Was momentum conserved in this collision?
yes
Position, velocity and acceleration of an oscillating mass on a spring are shown as a function of time. What is the frequency of the oscillations?
~0.4/s
You hear the sound of the ring of a distant cannon 5 seconds after seeing the flash. How far are you from the cannon?
~1700 m
Demo: Measure the frequency or period of a 0.1 kg mass oscillating on a spring. What is the spring constant of this spring?
~3 N/m
A student sees the following question on an exam: A flywheel with mass 120 kg and radius 0.6 m, starting at rest, has an angular acceleration of 0.1 rad/s2 . How many revolutions has the wheel undergone after 10 s? Which single formula might the student use to answer the question?
θf = θi + ωi (tf - ti )+ ½ α(tf - ti )^2
A small wheel and a large wheel are connected by a belt. The small wheel is turned at a constant angular speed ωs . How does the angular speed of the large wheel ωL compare to that of the small wheel?
ωs > ωL