Physics Final Exam
Two arrangements of a battery, bulb and wire are shown in the diagram. Which of the arrangements will light the bulb?
(a) only
Two circuit diagrams are shown. Which one, if either, will cause the lightbulb to light?
(b)
If 2 people can knit a total of 12 socks per hour, how many socks can five people knit in an 8 hour work day?
240
A car travels with an average speed of 26 m/s. What is this speed in km/h?
Average speed in km/h = (26 m/s1000 m/km)× 3600 s/h = 93.6 km/h
A car travels with an average speed of 26 m/s. What is this speed in km/s?
Average speed in km/s = 26 m/s divided by 1000 m/km=0.026 km/s
Equal forces are used to move blocks A and B across the floor. Block A has twice the mass of block B, but block B moves twice the distance moved by block A. Which block, if either, has the greater amount of work done on it?
Block B
Which of the following are the primary advantages of the metric system over the older English system?
Conversions are simple.
A +3.4 × 10−6 C test charge experiences forces from two other nearby charges: a 29-N force due east and an 15-N force due west. What is the direction of the electric field at the location of the test charge?
East
What is the difference, if any, of electric current and electric charge?
Electric current is moving electric charges.
Impulse is defined as the average force acting on an object multiplied by the time the force acts. If we let I represent impulse, F the average force, and t the time, which of the following equations is the correct definition?
I = Ft
A fullback with a mass of 107 kg and a velocity of 3.2 m/s due north collides head-on with a defensive back with a mass of 78 kg and a velocity of 5.6 m/s due south. If they stick together and external forces can be ignored, what direction will they be traveling immediately after they collide?
If they stick together and if external forces are ignored, they will be traveling due south immediately after the collision.
Suppose that the physics instructor pictured in the figure gives the bowling ball a push as she releases it. Where will the ball return to?
It will hit her in the chin.
A car travels around a flat (nonbanked) curve with constant speed, turning leftwards. In which direction is the net force on the car?
Leftwards
In the situation pictured in the figure, if there is a frictional force opposing the motion of the block, what is the sign of the work done by the frictional force?
Negative
A dropped ball gains speed as it falls. Can the velocity of the ball be constant in this process? Multiple Choice
No
A transformer has 18 turns of wire in its primary coil and 90 turns in its secondary coil. Is this a step-down transformer?
No
Four railroad cars, all with the same mass of 25000 kg, are at rest on a track, as shown in the following figure. A fifth car of identical mass approaches them with a velocity of 9 m/s (to the right). This car collides and couples with the other four cars. Is kinetic energy conserved in this collision?
No
Which of the following science fields is most fundamental?
Physics
In the circuit diagram shown, R1, R2, and R3 are three resistors of different values. R3 is greater than R2, and R2 is greater than R1. ε is the electromotive force of the battery whose internal resistance is negligible. Which of the three resistors has the greatest current flowing through it?
R3
In which of these relations will S double if T is doubled?
S = 10T
A 9-kg block being pushed across a table by a force P has an acceleration of 3 m/s2. If the magnitude of P is 38 N, what is the magnitude of the frictional force acting upon the block?
The magnitude of the frictional force acting upon the block is 11. f=38 N−(9 kg×3 m/s2)= 11N
A ball traveling in a circle with a constant speed of 12 m/s has a centripetal acceleration of 20 m/s2. What is the radius of the circle?
The radius of the circle is 7.2 ± 2% m. r=(12m/s)220 m/s2=7.2 m
A weight of 50 N is located at a distance of 8 cm from the fulcrum of a simple balance beam. At what distance from the fulcrum should a weight of 25 N be placed on the opposite side in order to balance the system?
The required distance from the fulcrum to balance the system is 16 cm. d2 = F1⋅d1F2 = 50 N⋅ 8 cm25 N = 16 cm
Suppose that a guitar string has a length of 0.88 m, a mass of 4.3 g, and a tension of 75.6 N. What is the speed of a wave on this string?
The speed of the wave on the string is 124.21 m/s. ν=Fμ−−√=75.6 N4.8864 × 10−3 kg/m
A bullet is fired horizontally with an initial velocity of 800 m/s at a target located 650 m from the rifle. How much time is required for the bullet to reach the target?
The time required for the bullet to reach the target is 0.8125s. t=dv0=650 m800 m/s=0.8125 s
A projectile is fired at an angle such that the vertical component of its velocity and the horizontal component of its velocity are both equal to 105 m/s. Using the approximate value of g = 10 m/s2, how long does it take for the ball to reach its high point?
The time taken to reach the high point is 10.5. t=va=105 m/s10 m/s2=10.5 s
An object moving horizontally across a table is observed to slow down. Which of the following statements is the correct explanation?
There is a net backwards horizontal force on the object.
How are Newton's first two laws of motion related to each other?
They are related to each other since the first law is a special case of the second law.
A person claiming to have paranormal powers states that she can predict which card will come up next in a shuffled deck of cards simply by exercising her mental powers. Is this a testable claim?
Yes
A wave pulse is transmitted down a Slinky, but the Slinky itself does not change position. Does a transfer of energy take place in this process?
Yes
A car traveling with an initial velocity of 16 m/s accelerates at a constant rate of 2.8 m/s2 for 3 seconds. What distance does the car travel during this process?
d=(16 m/s×3 s)+12(2.8 m/s2×(3 s)2)=60.6 m
How many poles can a bar magnet have?
only two poles
A horizontal wire is oriented along a north-south line, and a compass is placed above it. How, if at all, will the compass needle deflect if a strong electric current flows through the wire?
the compass will orient itself in the east-west direction
A ball hangs from a string attached to the ceiling, as shown in the diagram. What forces act on the ball?
the weight force, and the tension force
In the situation pictured in the diagram, what is the sign of the work done by the normal force of the floor pushing upwards on the block?
zero, the normal force does no work
List the following volumes in descending order.
-Gallon -Liter -Milliliter -Quart
List the following lengths in descending order.
-Mile -Kilometer -Foot -Inch -Centimeter
A ball hangs from a string attached to the ceiling, as shown in the diagram. What is the reaction force of the following forces on the ball?
-The gravitational force of the ball on the earth: The weight force -The force of the ball on the string: The tension force
A new system of units is invented where the basic unit of length is the "dak." The "dak" is defined as equal to 2 inches, and there are 2.54 centimeters in an inch. How many "daks" are there in a centimeter?
0.197
The metric system of units is based on which number?
10
One inch is defined as 2.54 centimeters. The correct expression for a one-inch length, expressed in meters, is
2.54 × 10-2 meters.
A fullback with a mass of 107 kg and a velocity of 3.2 m/s due north collides head-on with a defensive back with a mass of 78 kg and a velocity of 5.6 m/s due south. Calculate the initial momentum of the each player
342.4 ± 2% kg·m/s north and 436.8 ± 2% kg.m/s south. p=mv=(107 kg)×(3.2 m/s)p=mv=(107 kg)×(3.2 m/s) p=342.4 kg⋅m/s
An ice skater with a mass of 68 kg pushes off against a second skater with a mass of 30 kg. Both skaters are initially at rest. If the larger skater moves off with a speed of 2.8 m/s in the positive direction, what is the corresponding speed of the smaller skater?
6.3467 ± 2% m/s In the negative direction. p=−190.4 kg⋅m/s 30 kg
Students often fail to include units with their answers. Science teachers say that units are important. In which one of the following situations would you insist that units be included?
A friend offers you two per mile to help pay for gas on a trip.
Why did Aristotle believe that heavier objects fall faster than lighter objects?
Aristotle believed that heavier objects felt a larger force and a larger force made the object move faster.
If you increase the frequency with which you are moving the end of a Slinky back-and-forth, how does the wavelength of the Slinky change?
It decreases.
A driver states that she was doing 80 when stopped by the police. What is the problem with this statement in terms of its clarity?
It has no units.
Suppose that we increase the tension in a rope, keeping the frequency of oscillation of the end of the rope the same. What effect does this have on the wavelength of the wave produced?
It increases.
What type of collision must have occurred if momentum was conserved?
It is impossible to tell.
Two masses are separated by a distance r. If the distance is doubled how does the force between them change, if at all?
It is reduced by a factor of 4.
The north pole of a hand-held bar magnet is brought near the north pole of a second bar magnet lying on the tablet. How will the second magnet tend to move?
It will be repelled and move away.
If we decrease the potential difference across a resistance in a circuit, how will the current flowing through that resistance change?
It will decrease.
Which of the following is a correct metric unit for volume?
Liters
Which system of units is the most widely used throughout the world today?
Metric
Over the years, there have been several credible claims by experienced observers of sightings of Unidentified Flying Objects (UFOs). Despite this, scientists have shied away from taking up serious study of UFOs, although there are ongoing searches for signals from extraterrestrial intelligent beings. Which of the following would be good reasons why scientists have not taken UFOs seriously? (Check all that apply.)
Most data is eyewitness testimony, seeing UFOs seems to be random, and video evidence can be altered.
Historians sometimes develop theories to explain observed patterns of different countries. Are these theories testable in the same sense as a theory in physics?
No
The electric potential increases from 52 V to 367 V from the bottom plate to the top plate of a parallel-plate capacitor. A −4 ×10-3 C charge is moved from the bottom plate to the top plate. Does the potential energy increase in the process?
No
A ball hangs from a string attached to the ceiling, as shown in the diagram. What is the direction of the net force acting on the ball?
None, the net force equals zero.
A car traveling with a constant speed rounds a curve in the highway. What is the acceleration of the car?
Nonzero
How is the wavelength of the fundamental standing wave in a tube open at both ends compared with the wavelength for the fundamental wave in a tube open at just one end?
The both-ends-open tube's fundamental wavelength is smaller.
A bullet is fired horizontally with an initial velocity of 800 m/s at a target located 650 m from the rifle. Using the approximate value of g = 10 m/s2, how far does the bullet fall in this time?
The bullet falls by a distance of 330. d=12at2=10 m/s2×(0.8125 s)22=3.3008 meters
Suppose that a bullet is fired from a rifle in outer space where there are no appreciable forces due to gravity or air resistance acting on the bullet. Which is the correct situation for the bullet after it is fired if it does not hit anything?
The bullet will remain at the same speed.
The potential energy of a +8 × 10−6 C charge decreases from 0.62 J to 0.34 J when it is moved from point A to point B. What is the magnitude of the change in electric potential between these two points?
The change in electric potential between the two points is 35000 ± 2% V. ΔV= ΔPEq= (0.62 J− 0.34 J)8 × 10−6 C =35000 V
The electric potential increases from 52 V to 367 V from the bottom plate to the top plate of a parallel-plate capacitor. A −4 ×10-3 C charge is moved from the bottom plate to the top plate. What is the magnitude of the change in potential energy of the charge?
The change in potential energy of the charge has magnitude 1.26 J. |ΔPE|= |qΔV|=∣∣(−4×10−3 C)×(367 V−52 V)∣∣ = 1.26 J
Three resistors - R1 = 18 Ω, R2 = 26 Ω, and R3 = 28 Ω are connected to a 12-V battery as shown in the figure. The internal resistance of the battery is negligible. What is the current coming from the battery?
The current coming from the battery is 0.167 A. I=12 V72 Ω=0.1667 A
Four 30-Ω resistors are connected in series to a 18-V battery of negligible internal resistance. Calculate the current flowing through each resistor.
The current flowing through each resistor is 0.15 A. I=18 V 120 Ω= 0.15 A
Three resistors - R1 = 18 Ω, R2 = 26 Ω, and R3 = 28 Ω are connected to a 12-V battery as shown in the figure. The internal resistance of the battery is negligible. What is the current through the 18-Ω resistor?
The current is 0.167 A. I=VR=12 V72 Ω
Three identical resistors, where R1 = 48 Ω, are connected in parallel with one another as shown. Then the parallel combination is connected to a 12-V battery whose internal resistance is negligible. How much current flows through each resistor in the combination?
The current that flows through each resistor is 0.25 A. I=VR1=12 V48 Ω
A charge of 32 C passes at a steady rate through a resistor in 7 s. Determine the current through the resistor.
The current through the resistor is 4.57 A. I=qt=32 C7 s= 4.5714 A
Suppose that a skydiver wears a specially lubricated suit that reduces air resistance to a small constant force that does not increase as the diver's velocity increases. In this situation which of the following statements is correct?
The diver will no longer experience a terminal velocity.
A clothes dryer uses 6950 W of power when connected to a 220-V ac line. How much current does the dryer draw from the line?
The dryer draws a current of 31.6 A. I=PV=6950 W220 V=31.5909 A
A transformer has 18 turns of wire in its primary coil and 90 turns in its secondary coil. If an alternating voltage with an effective voltage of 117 V is applied to the primary, what is the effective voltage induced in the secondary coil.
The effective voltage induced in the secondary coil is 585 V. ΔV2=117 V×(9018)
Three identical resistors, where R1 = 48 Ω, are connected in parallel with one another as shown. Then the parallel combination is connected to a 12-V battery whose internal resistance is negligible. What is the equivalent resistance of this parallel combination?
The equivalent resistance of this parallel combination is 16 Ω. =1R1+1R2+1R3=148 Ω+148 Ω+148 Ω
Two masses are attracted by a gravitational force of 9.2 N. What will the force of attraction be if the distance between the two masses is quadrupled?
The force of attraction will be 0.575 N. F(force at four times the distance)=9.2 N16=0.575 N
Two masses are attracted by a gravitational force of 0.26 N. What will the force of attraction be if the distance between the two masses is halved?
The force of attraction will be 1.04 N. F (force at half the distance)=0.26 N0.25=1.04 N
The tablecloth trick is where a tablecloth is rapidly pulled out from under some dinnerware without disturbing the dinnerware appreciably. The dinnerware does move a small amount though. Which of the following explanations is correct for this situation?
The force of friction from the moving tablecloth only acts for a short time.
An organ pipe closed at one end and open at the other has a length of 5.7 m. What is the frequency associated with this standing wave if the speed of sound is 340 m/s?
The frequency of the standing wave is 15 Hz. f=νλ=340 m/s22.8 m=14.9123 Hz
A wave on a string has a speed of 14.5 m/s and a period of 0.1 s. What is the frequency of the wave?
The frequency of the wave is 10 ± 2% Hz. f=1T=10.1 s=10 Hz
A string with a length of 1.55 m is fixed at both ends. If waves travel with a speed of 130 m/s on this string, what is the frequency associated with this longest wavelength?
The frequency of the wavelength is 42 Hz. f=νλ=ν2L=130 m/s3.1 m=41.9355 Hz
A sprinter accelerates at the beginning of a 100-meter race and then tries to maintain a maximum speed throughout the rest of the race. Which of the following forces is responsible for accelerating the sprinter at the start of the race?
The friction force exerted by the ground on the runner's shoe.
An 7-kg block is acted upon by three horizontal forces A = 7 N, B = 17 N, and C = 15 N, as shown in the diagram. What is the horizontal acceleration of the block?
The horizontal acceleration is 1.2857 ± 2% m/s2. a=Fnetm=9 N7 kg=1.2857 m/s2
A ball experiences a change in momentum of 64 kg·m/s. What is the magnitude of the impulse acting on the ball?
The impulse acting on the ball is 64 Ns. mpulse=change in momentum(Δp)
Four railroad cars, all with the same mass of 25000 kg, are at rest on a track, as shown in the following figure. A fifth car of identical mass approaches them with a velocity of 9 m/s (to the right). This car collides and couples with the other four cars. What is the kinetic energy of all the five cars just after the collision?
The kinetic energy of all five cars after the collision is 1.8× 103 J. KE=12(125000 kg)×(95m/s)2
Four railroad cars, all with the same mass of 25000 kg, are at rest on a track, as shown in the following figure. A fifth car of identical mass approaches them with a velocity of 9 m/s (to the right). This car collides and couples with the other four cars. Determine the kinetic energy of car 5 before the collision.
The kinetic energy of car 5 is 225000× 103 J. KE=12(25000 kg)×(9 m/s)2
A roller-coaster car has a potential energy of 750 kJ and a kinetic energy of 165 kJ at point A in its travel. At the low point of the ride, the potential energy is zero, and 60 kJ of heat has been generated by friction since it left point A. What is the kinetic energy of the roller coaster at this low point?
The kinetic energy of the roller coaster at its low point is 855 ± 2% kJ. 750 kJ + 165 kJ - 60 kJ = 855 kJ
An organ pipe closed at one end and open at the other has a length of 5.7 m. What is the longest possible wavelength for the interfering sound waves that can form a standing wave in this pipe?
The longest possible wavelength for the interfering sound waves is 22.8 ± 2% m. λ=4L=4×5.7 m=22.8 m
A string with a length of 1.55 m is fixed at both ends. What is the longest possible wavelength for the traveling waves that can interfere to form a standing wave on this string?
The longest possible wavelength is 3.1 m. λ=2L=2×1.55 m=3.1 m
A ball experiences a change in momentum of 64 kg·m/s. If the time of interaction is 0.15 s, what is the magnitude of the average force acting on the ball? Round the final answer to the nearest whole number.
The magnitude of the average force acting on the ball is 427 N. F=64 kg⋅m/s0.15 s
A 0.35-kg ball moving in a circle at the end of a string has a centripetal acceleration of 10 m/s2. Determine the magnitude of the centripetal force exerted by the string on the ball to produce this acceleration.
The magnitude of the centripetal force is 3.5 N. Fnet= (0.35 kg)(10 m/s2) = 3.5 N
A +3.4 × 10−6 C test charge experiences forces from two other nearby charges: a 29-N force due east and an 15-N force due west. Determine the magnitude of the electric field at the location of the test charge.
The magnitude of the electric field at the location of the test charge is 4.1176× 106 N/C. E= Feq= ∣∣(29 N− 15N)3.4 × 10−6 C∣∣= 4.1176×106 N/C
Imagine another universe, where alternate electrons and protons have electric charge with magnitude 2.2 × 10−19 C but opposite signs. In that universe, an alternate electron and an alternate proton are situated in an "alternate hydrogen atom", separated by a distance of 5.29 × 10−11 m. Coulomb's law is valid in that universe, and Coulombs constant is the same as in our universe, 9 × 109 N·m2/C2. Calculate the magnitude of the electrostatic force exerted on the alternate electron by the alternate proton.
The magnitude of the electrostatic force is 15.566 ± 2% × 10-8 N. = kq1q2r2= (9 × 109 N⋅m2/C2)(2.2 × 10−19C)(2.2 × 10−19C)(5.29 × 10−11 m)2= 15.566×10−8 N
Two charged particles exert an electrostatic force of 25 N on each other. What will the magnitude of the electrostatic force be if the distance between the two charges is reduced to one-third of the original distance?
The magnitude of the electrostatic force is 225 N. F= 9×25 N = 225 N
Two 700-kg masses (1543 lb) are separated by a distance of 40 m. Using Newton's law of gravitation, find the magnitude of the gravitational force exerted by one mass on the other. (Use G = 6.67 × 10-11 N·m2/kg2.)
The magnitude of the gravitational force exerted by one mass on the other is 20.4269 ± 2% × 10-9 N. F=(700 kg × 700 kg) ×(6.67× 10−11 Nm2/kg2)(40 m)2=20.4269×10−9 N
A particle with a charge of 0.6 C is moving at right angles to a uniform magnetic field with a strength of 0.5 T. The velocity of the charge is 800 m/s. What is the magnitude of the magnetic force exerted on the particle?
The magnitude of the magnetic force exerted on the particle is 240 N. F=0.5 T×0.6 C×800 m/s
A straight segment of wire has a length of 7 cm and carries a current of 27 A. It is oriented at right angles to a magnetic field of 0.5 T. Calculate the magnitude of the magnetic force on the segment of wire.
The magnitude of the magnetic force on the segment of wire is 0.945 N. F=(27 A)×(7100 m)×0.5 T
A ball is thrown upward, from the ground, with an initial velocity of 14 m/s. The approximate value of g = 10 m/s2. Take the upward direction to be positive. What is the magnitude and the direction of the velocity of the ball 1 second after it is thrown?
The magnitude of the velocity is 4 and the motion is upward v=v0+atv=v0+at =14 m/s+(-10 m/s2×1 s)=4 m/s
A ball is thrown upward, from the ground, with an initial velocity of 14 m/s. The approximate value of g = 10 m/s2. Take the upward direction to be positive. What is the magnitude and the direction of the ball's velocity 2 seconds after it is thrown?
The magnitude of the velocity is 6 ± 2% m/s, and the motion is downward. v=v0+at=14 m/s+(-10 m/s2×2 s)
The acceleration due to gravity on the moon is approximately one-sixth the gravitational acceleration near the Earth's surface. If a rock is transported from the Earth to the moon which of the following will occur?
The mass of the rock will remain the same while its weight will decrease.
Suppose that a guitar string has a length of 0.88 m, a mass of 4.3 g, and a tension of 75.6 N. What is the mass per unit length of this string?
The mass per unit length of the string is 4.8864 ± 2% × 10-3 kg/m. μ=mL=0.0043 kg0.88 m=4.8864 ×10−3 kg/m
Two objects collide under conditions where total momentum is conserved. Is the momentum conserved for each object?
The momentum of each object is not conserved separately.
A 9-kg block being pushed across a table by a force P has an acceleration of 3 m/s2. What is the net force acting on the block?
The net force acting on the block is 27 ± 2% N. Fnet=9 kg×3 m/s2 =27 N
A 3-kg block is observed to accelerate at a rate twice that of a 6-kg block.
The net force on the 3-kg block must be equal to that acting on the 6-kg block.
An 7-kg block is acted upon by three horizontal forces A = 7 N, B = 17 N, and C = 15 N, as shown in the diagram. What is the net horizontal force acting on the block?
The net horizontal force acting on the block is 9 ± 2% N. Fnet=7 N+17 N−15 N= 9N
Two forces are applied to a merry-go-round with a radius of 3.6 m as shown in the following diagram. One force has a magnitude of 90 N and the other a magnitude of 40 N. Take the torque caused by the 90-N force to be positive. Calculate the net torque acting on the merry-go-round.
The net torque acting on the merry-go-round is 180 N·m. τtotal = τ90 N+τ40 N = (324 N⋅m)+(-144 N⋅m) = 180 N⋅m
A step-down transformer is used to convert an ac voltage of 120 V to 19 V to power an electric train. If there are 430 turns in the primary coil, how many turns should be there in the secondary coil?
The number of turns in the secondary coil is 68 turns. N2=430×(19 V120 V)
A step-up transformer is designed to produce 1840 V from a 122-V ac source. If there are 384 turns on the secondary coil, how many turns should be wound on the primary coil?
The number of turns that should be wound on the primary coil is 25. N1=384×(122 V1840 V)
Suppose your phone has not rung in several days, but a friend tells you he has tried to call. Which of the following statements would be scientific hypotheses? Check all that apply.
The phone has been turned off, your phone number has been given to someone else, your ringer has been turned off, and your friend is lying.
A 14-V battery in a simple circuit produces a current of 2 A through the circuit. How much power is being delivered by the battery?
The power delivered by the battery is 28 W. P=V×I=14 V×2 A
A projectile is fired at an angle such that the vertical component of its velocity and the horizontal component of its velocity are both equal to 105 m/s. What horizontal distance does the projectile travel in this time?
The projectile travels a horizontal distance of 1103. d=v0t=105 m/s×10.5 s=1102.5 m
Two forces are applied to a merry-go-round with a radius of 3.6 m as shown in the following diagram. One force has a magnitude of 90 N and the other a magnitude of 40 N. Take the torque caused by the 90-N force to be positive. What is the torque about the axle of the merry-go-round due to the 40-N force?
The torque about the axle of the merry-go-round due to the 40-N force is -144 ± 2% N·m. τ = F⋅R =−40 N×3.6 m =-144 N⋅m (Negative sign indicates the direction of the resulting torque)
Two forces are applied to a merry-go-round with a radius of 3.6 m as shown in the following diagram. One force has a magnitude of 90 N and the other a magnitude of 40 N. Take the torque caused by the 90-N force to be positive. What is the torque about the axle of the merry-go-round due to the 90-N force?
The torque about the axle of the merry-go-round due to the 90-N force is 324 N·m. τ = F⋅R =90 N⋅3.6 m = 324 N⋅m
A force of 30 N is applied at the end of a wrench handle that is 24 cm long. The force is applied in a direction perpendicular to the handle. What is the torque applied to the nut by the wrench?
The torque applied to the nut by the wrench is 7.2 ± 2% N·m. τ = F⋅l = 30 N⋅(24 cm×1 m100 cm)= 7.2 N⋅m
A force of 30 N is applied at the end of a wrench handle that is 24 cm long. The force is applied in a direction perpendicular to the handle. Calculate the torque if the force is applied halfway up the handle instead of at the end.
The torque on the nut is 3.6 N·m. τ = F⋅l = 30 N⋅(12×24 cm×1 m100 cm)=3.6 N⋅m
Three identical resistors, where R1 = 48 Ω, are connected in parallel with one another as shown. Then the parallel combination is connected to a 12-V battery whose internal resistance is negligible. What is the total current through the combination?
The total current through the combination is 0.75 A. I=VR=12 V16 Ω
An ice skater with a mass of 68 kg pushes off against a second skater with a mass of 30 kg. Both skaters are initially at rest. What is the total momentum of the system after they push off?
The total momentum of the system after the skaters push off is 0 kg·m/s
A fullback with a mass of 107 kg and a velocity of 3.2 m/s due north collides head-on with a defensive back with a mass of 78 kg and a velocity of 5.6 m/s due south. What is the total momentum of the system before the collision?
The total momentum of the system before the collision is 94.4 south. p=436.8 kg⋅m/s south−342.4 kg⋅m/s north
Three resistors - R1 = 18 Ω, R2 = 26 Ω, and R3 = 28 Ω are connected to a 12-V battery as shown in the figure. The internal resistance of the battery is negligible. What is the total resistance in the circuit?
The total resistance in the circuit is 72 Ω. Rseries=18 Ω+26 Ω+28 Ω
A railroad car collides and couples with a second railroad car that is standing still. If the external forces acting on the two cars are negligible, how will the velocity of the first car change after the collision?
The velocity of the first car will decrease.
Four 30-Ω resistors are connected in series to a 18-V battery of negligible internal resistance. Determine the voltage difference across each resistor.
The voltage difference across each resistor is 4.5 V. V= IR=(0.15 A)×(30 Ω)=4.5 V
Three resistors - R1 = 18 Ω, R2 = 26 Ω, and R3 = 28 Ω are connected to a 12-V battery as shown in the figure. The internal resistance of the battery is negligible. What is the voltage difference across the 26-Ω resistor?
The voltage difference is 4.34 V. ΔV=IR=0.1667 A×26 Ω
Suppose that water waves coming into a dock have a velocity of 2.1 m/s and a wavelength of 4.2 m. With what frequency do these waves meet the dock?
The water waves meet the dock with a frequency of 0.5 Hz. f=νλ=2.1 m/s4.2 m=0.5 Hz
A wave on a rope is shown as in the diagram, where L = 17 m. If the frequency of the wave is 4 Hz, what is the wave speed?
The wave speed is 34 ± 2% m/s. ν=f×λ=4 Hz ×8.5 m=34 m/s
A string with a length of 7.75 m is fixed at both ends. If the string is plucked so that there are five nodes along the string in addition to those at either end, what is the wavelength of the interfering waves for this mode?
The wavelength of the interfering waves is 2.5833 ± 2% m. λ=L3=7.75 m3=2.5833 m
A wave on a string has a speed of 14.5 m/s and a period of 0.1 s. What is the wavelength of the wave?
The wavelength of the wave is 1.45 ± 2% m. λ=νf=14.5 m/s10 Hz=1.45 m
A wave on a rope is shown as in the diagram, where L = 17 m. What is the wavelength of this wave?
The wavelength of the wave is 8.5 ± 2% m. λ=L2=17 m2=8.5 m
How is the mass of an object different from its weight?
The weight of an object is the amount of force exerted on the object by gravity while the mass is the amount of matter in the object.
The acceleration due to gravity at the surface of the moon is 1.63 m/s2. What is the weight of an astronaut standing on the moon whose weight on Earth is 142 lb?
The weight of the astronaut on the moon is 23.6667 ± 2% lb. 142 lb6=23.6667 lb
A horizontally directed force of 40-N is used to pull a box through a distance of 1.5 m across a tabletop. How much work is done by the 40-N force?
The work done by the 40-N force is 60 J. W=F×d=40 N×1.5 m
Two balls with the same mass are each accelerated from rest by different net forces. The red ball attains twice the speed that the blue ball attains. How does the work done on the red ball compare with the work done on the blue ball?
The work done by the force on the red ball was four times that done on the blue ball.
A lever is used to lift a rock as shown in the diagram. How will the work done by the person on the lever compare with the work done by the lever on the rock if there are no dissipative forces?
The work done on the lever equals the work done on the rock.
Which, if either, exerts the larger gravitational force on the other?
They both exert the same force on each other.
magine another universe, where alternate electrons and protons have electric charge with magnitude 2.2 × 10−19 C but opposite signs. In that universe, an alternate electron and an alternate proton are situated in an "alternate hydrogen atom", separated by a distance of 5.29 × 10−11 m. Coulomb's law is valid in that universe, and Coulombs constant is the same as in our universe, 9 × 109 N·m2/C2. The direction of the electrostatic force exerted on the electron by the proton is along a straight line from the proton to the electron.
True
Three resistors - R1 = 18 Ω, R2 = 26 Ω, and R3 = 28 Ω are connected to a 12-V battery as shown in the figure. The internal resistance of the battery is negligible. Is the current flow through resistor R1 same as the current flow through resistor R3 in the given circuit?
Yes
For a real world pendulum is the total mechanical energy conserved?
almost, only a small amount is lost to friction
Which of the following units is NOT appropriate for measuring volume?
centimeter
The principal advantage of metric units over English units is that
conversions between metric units are easier.
A bird grabs a clam, carries it in its beak to a considerable height, and then drops it on a rock below, breaking the clam shell. Which is the correct energy conversion when the clam is dropped?
gravitational potential to kinetic
A slowly moving engine bumps into a string of coupled railroad cars standing on a siding. A wave pulse is transmitted down the string of cars as each one bumps into the next one. What type of wave is this?
longitudinal
What is the force exerted by one current-carrying wire on another due to?
magnetic effects
By expressing relationships between quantities using mathematics, we can
make our statements more compact and make manipulations easier.
A ball bounces off a wall with a velocity whose magnitude is less that it was before hitting the wall. What type of collision is this?
partially inelastic
A pendulum is pulled back from its equilibrium (center) position and then released. When the bob is halfway between the high point and the low point in its swing in what form(s) is the total energy of the bob?
partially kinetic, partially potential
For what time interval is the velocity constant?
t = 0 s to t = 2s
During what time interval does the object have the greatest acceleration?
t = 2 s to t = 4s
Which of these criteria best distinguish between explanations provided by science and those provided by religion?
testability
The engine of a car is part of the car and cannot push directly on the car in order to accelerate it. What external force acting on the car is responsible for the acceleration of the car on a level road surface?
the friction force of the ground on the tires
Two forces, F1 and F2, of equal magnitude act on a box as shown in the diagram.
the object is not accelerating in the horizontal direction
Suppose that your car will not start and you form the hypothesis that the battery is dead. Which of the following would be a test of that hypotheses? Check all that apply.
turning the headlights on, and replacing the battery with another new battery
The tablecloth trick is where a tablecloth is rapidly pulled out from under some dinnerware without disturbing the dinnerware appreciably. For which of the following situations would the trick still work?
using a sheet of wax paper instead of a tablecloth
A car traveling with an initial velocity of 16 m/s accelerates at a constant rate of 2.8 m/s2 for 3 seconds. What is its velocity at the end of this time?
v=16 m/s+(2.8 m/s2×3 s)=24.4 m/s
Consider a runner traveling with an initial velocity of 3.4 m/s in the positive direction accelerates at a constant rate of 1.9 m/s2 for a time of 5 seconds. What is his velocity at the end of this time?
v=3.4 m/s+(1.9 m/s2×5 s)=12.9 m/s