AP Physics Chapter 7 & 8 practice quizzes
A car traveling at 20 m/s rounds a curve so that its centripetal acceleration is 5 m/s^2. What is the radius of the curve? A. 4 m B. 8 m C. 80 m D. 160 m E. 640 m
Answer: C
Consider a hypothetical planet in our solar system whose average distance from the Sun is about four times that of Earth. Determine the orbital period for this hypothetical planet. A. 0.25 year B. 2.5 years C. 4 years D. 8 years E. 16 years
Answer: D
An indoor track is to be designed such that each end is a banked semi-circle with a radius of 24 m. What should the banking angle be for a person running at speed v = 6.0 m/s? A. 8.7° B. 11° C. 14° D. 22° E. 45°
Answer: A
The maximum speed at which a car can safely negotiate a frictionless banked curve depends on all of the following except A. the mass of the car. B. the angle of banking. C. the diameter of the curve. D. the radius of the curve. E. the acceleration due to gravity.
Answer: A
A 1000-kg car travels along a straight 500-m portion of highway (from A to B) at a constant speed of 10 m/s. At B, the car encounters an unbanked curve of radius 50 m. The car follows the road from B to C traveling at a constant speed of 10 m/s while the direction of the car changes from east to south. R-1 Ref 5-2 What is the magnitude of the acceleration of the car as it travels from B to C? A. 2 m/s^2 B. 5 m/s^2 C. 10 m/s^2 D. 20 m/s^2 E. zero m/s^2
Answer: A
A 1500-kg car travels at a constant speed of 22 m/s around a circular tack that has a radius of 85 m. R-1 Ref 5-5 Which statement is true concerning this car? A. The velocity of the car is changing. B. The car is characterized by constant velocity. C. The car is characterized by constant acceleration. D. The car has a velocity vector that points along the radius of the circle. E. The car has an acceleration vector that is tangent to the circle at all times.
Answer: A
A 2.0-kg hoop rolls without slipping on a horizontal surface so that its center proceeds to the right with a constant linear speed of 6.0 m/s. R-2 Ref 9-3 Which one of the following statements is true concerning the angular momentum of this hoop? A. It points into the paper. B. It points out of the paper. C. It points to the left. D. It points to the right. E. It varies from point to point on the hoop.
Answer: A
A 2400-kg satellite is in a circular orbit around a planet. The satellite travels with a constant speed of 6.67 ´ 103 m/s. The radius of the circular orbit is 8.92 ´ 106 m. R-1 Ref 5-3 At the instant shown in the figure, which arrow indicates the direction of the net force on the satellite? A. ----> B. <----- C. ^ | | D. | | v E. \ \ >
Answer: A
A long thin rod of length 2L rotates with a constant angular acceleration of 10 rad/s2 about an axis that is perpendicular to the rod and passes through its center. R-2 Ref 8-6 What is the ratio of the angular speed (at any instant) of a point on the end of the rod to that of a point a distance L/2 from the end of the rod? A. 1:1 B. 1:2 C. 2:1 D. 4:1 E. 1:4
Answer: A
A rocket orbits a planet in a circular orbit at a constant speed as shown in the drawing. Note the arrows shown: R-2 Ref 5-6 At the instant shown in the drawing, which arrow indicates the direction of the acceleration of the rocket? A. 1 B. 2 C. 3 D. 4 E. 5
Answer: A
A solid sphere and a hollow sphere each of mass M and radius R are released at the same time from the top of an inclined plane. Which one of the following statements is necessarily true? A. The solid sphere will reach the bottom first. B. The hollow sphere will reach the bottom first. C. Both spheres will reach the bottom at the same time. D. The solid sphere will reach the bottom with the greater kinetic energy. E. The hollow sphere will reach the bottom with the greater kinetic energy.
Answer: A
Consider the following four objects: a hoop a solid sphere a flat disk a hollow sphere Each of the objects has mass M and radius R. The axis of rotation passes through the center of each object, and is perpendicular to the plane of the hoop and the plane of the flat disk. Which object requires the largest torque to give it the same angular acceleration? A. the hoop B. the flat disk C. the solid sphere D. the hollow sphere E. both the solid and the hollow spheres
Answer: A
Consider the following three objects, each of the same mass and radius: (1) a solid sphere (2) a solid disk (3) a hoop All three are released from rest at the top of an inclined plane. The three objects proceed down the incline undergoing rolling motion without slipping. In which order do the objects reach the bottom of the incline? A. 1, 2, 3 B. 2, 3, 1 C. 3, 1, 2 D. 3, 2, 1 E. All three reach the bottom at the same time.
Answer: A
In an amusement park ride, a small child stands against the wall of a cylindrical room that is then made to rotate. The floor drops downward and the child remains pinned against the wall. If the radius of the device is 2.15 m and the relevant coefficient of friction between the child and the wall is 0.400, with what minimum speed is the child moving if he is to remain pinned against the wall? A. 7.26 m/s B. 3.93 m/s C. 12.1 m/s D. 5.18 m/s E. 9.80 m/s
Answer: A
The world's largest Ferris wheel with a radius of 50.0 m is located in Yokohama City, Japan. Each of the sixty gondolas on the wheel takes 1.00 minute to complete one revolution when it is running at full speed. Note: Ignore gravitational effects. What is the centripetal acceleration of the gondola when the Ferris wheel is running at full speed? A. 0.548 m/s^2 B. 6.91 m/s^2 C. 2.21 m/s^2 D. 0.732 m/s^2 E. 6.28 m/s^2
Answer: A
Two uniform solid spheres, A and B have the same mass. The radius of sphere B is twice that of sphere A. The axis of rotation passes through each sphere. Which one of the following statements concerning the moments of inertia of these spheres is true? A. The moment of inertia of A is one-fourth that of B. B. The moment of inertia of A is one-half that of B. C. The moment of inertia of A is 5/4 that of B. D. The moment of inertia of A is 5/8 that of B. E. The two spheres have equal moments of inertia.
Answer: A
A ball moves with a constant speed of 4 m/s around a circle of radius 0.25 m. What is the period of the motion? A. 0.1 s B. 0.4 s C. 0.7 s D. 1 s E. 2 s
Answer: B
A car enters a horizontal, curved roadbed of radius 50 m. The coefficient of static friction between the tires and the roadbed is 0.20. What is the maximum speed with which the car can safely negotiate the unbanked curve? A. 5 m/s B. 10 m/s C. 20 m/s D. 40 m/s E. 100 m/s
Answer: B
A car travels in a circular path with constant speed. Which one of the following quantities is constant and non-zero for this car? A. linear velocity B. angular velocity C. centripetal acceleration D. angular acceleration E. total acceleration
Answer: B
A certain string just breaks when it is under 400 N of tension. A boy uses this string to whirl a 10-kg stone in a horizontal circle of radius 10 m. The boy continuously increases the speed of the stone. At approximately what speed will the string break? A. 10 m/s B. 20 m/s C. 80 m/s D. 100 m/s E. 400 m/s
Answer: B
A hollow cylinder of mass M and radius R rolls down an inclined plane. A block of mass M slides down an identical inclined plane. If both objects are released at the same time, A. the cylinder will reach the bottom first. B. the block will reach the bottom first. C. the block will reach the bottom with the greater kinetic energy. D. the cylinder will reach the bottom with the greater kinetic energy. E. both the block and the cylinder will reach the bottom at the same time.
Answer: B
A rocket orbits a planet in a circular orbit at a constant speed as shown in the drawing. Note the arrows shown: R-2 Ref 5-6 Suppose that the radius of the circular path is R when the speed of the rocket is v and the acceleration of the rocket has magnitude a. If the radius and speed are increased to 2R and 2v respectively, what is the magnitude of the rocket's subsequent acceleration? A. a/2 B. 2a C. a D. 4a E. 8a
Answer: B
A top is spinning counterclockwise as shown in the figure. It is also moving to the right with a linear speed v. What is the direction of the angular velocity? A. downward B. upward C. left D. right E. into the paper
Answer: B
Sara puts a box into the trunk of her car. Later, she drives around an unbanked curve that has a radius of 48 m. The speed of the car on the curve is 16 m/s, but the box remains stationary relative to the floor of the trunk. Determine the coefficient of static friction for the box on the floor of the trunk. A. 0.42 B. 0.54 C. 0.17 D. 0.33 E. This cannot be determined without knowing the mass of the box.
Answer: B
Which force is responsible for holding a car in an unbanked curve? A. the car's weight B. the force of friction C. the reaction force to the car's weight D. the vertical component of the normal force E. the horizontal component of the normal force
Answer: B
Which one of the following statements concerning the moment of inertia I is false? A. I may be expressed in units of kg • m2. B. I depends on the angular acceleration of the object as it rotates. C. I depends on the location of the rotation axis relative to the particles that make up the object. D. I depends on the orientation of the rotation axis relative to the particles that make up the object. E. Of the particles that make up an object, the particle with the smallest mass may contribute the greatest amount to I.
Answer: B
A 2.0-kg solid disk rolls without slipping on a horizontal surface so that its center proceeds to the right with speed 5.0 m/s. The point A is the uppermost point on the disk and the point B is along the horizontal line that connects the center of the disk to the rim. R-1 Ref 8-4 Which one of the following statements concerning the direction of the disk's angular velocity is true? A. It points to the left. B. It points to the right. C. It points into the paper. D. It points out of the paper. E. It varies from point to point on this disk.
Answer: C
A ball of mass M moves in a circular path on a horizontal, frictionless surface. It is attached to a light string that passes through a hole in the center of the table. If the string is pulled down, thereby reducing the radius of the ball's path, the speed of the ball is observed to increase. Complete the following sentence: This occurs because O A. the linear momentum of the ball is conserved. O B. it is required by Newton's first law of motion. O C. the angular momentum of the ball is conserved. O D. the angular momentum of the ball must increase. O E. the total mechanical energy of the ball must remain constant.
Answer: C
A circular hoop rolls without slipping on a flat horizontal surface. Which one of the following is necessarily true? A. All points on the rim of the hoop have the same speed. B. All points on the rim of the hoop have the same velocity. C. Every point on the rim of the wheel has a different velocity. D. All points on the rim of the hoop have acceleration vectors that are tangent to the hoop. E. All points on the rim of the hoop have acceleration vectors that point toward the center of the hoop.
Answer: C
A long thin rod of length 2L rotates with a constant angular acceleration of 10 rad/s2 about an axis that is perpendicular to the rod and passes through its center. R-2 Ref 8-6 What is the ratio of the centripetal acceleration of a point on the end of the rod to that of a point a distance L/2 from the end of the rod? A. 1:1 B. 1:2 C. 2:1 D. 4:1 E. 1:4
Answer: C
A long thin rod of length 2L rotates with a constant angular acceleration of 10 rad/s2 about an axis that is perpendicular to the rod and passes through its center. R-2 Ref 8-6 What is the ratio of the tangential acceleration of a point on the end of the rod to that of a point a distance L/2 from the end of the rod? A. 1:1 B. 1:2 C. 2:1 D. 4:1 E. 1:4
Answer: C
A long thin rod of length 2L rotates with a constant angular acceleration of 10 rad/s2 about an axis that is perpendicular to the rod and passes through its center. R-2 Ref 8-6 What is the ratio of the tangential speed (at any instant) of a point on the end of the rod to that of a point a distance L/2 from the end of the rod? A. 1:1 B. 1:2 C. 2:1 D. 4:1 E. 1:4
Answer: C
A racecar is traveling at constant speed around a circular track. What happens to the centripetal acceleration of the car if the speed is doubled? A. It remains the same. B. It increases by a factor of 2. C. It increases by a factor of 4. D. It is decreased by a factor of one-half. E. It is decreased by a factor of one-fourth.
Answer: C
A satellite is placed in equatorial orbit above Mars, which has a radius of 3397 km and a mass MM = 6.40 ´ 1023 kg. The mission of the satellite is to observe the Martian climate from an altitude of 488 km. What is the orbital period of the satellite? A. 9.18 ´ 102 s B. 3.62 ´ 103 s C. 7.36 ´ 103 s D. 1.08 ´ 105 s E. 7.27 ´ 1012 s
Answer: C
A spaceship is in orbit around the earth at an altitude of 12 000 miles. Which one of the following statements best explains why the astronauts experience "weightlessness?" A. The centripetal force of the earth on the astronaut in orbit is zero newtons. B. The pull of the earth on the spaceship is canceled by the pull of the other planets. C. The spaceship is in free fall and its floor cannot press upwards on the astronauts. D. The force of gravity decreases as the inverse square of the distance from the earth's center. E. The force of the earth on the spaceship and the force of the spaceship on the earth cancel because they are equal in magnitude but opposite in direction.
Answer: C
Callisto and Io are two of Jupiter's moons. The distance from Callisto to the center of Jupiter is approximately 4.5 times as far as that of Io. How does Callisto's orbital period, TC, compare to that of Io, TI? A. TC = 4.5TI B. TC = 21TI C. TC = 9.5TI D. TC = 0.2TI E. TC = 2.7TI
Answer: C
Consider a satellite in a circular orbit around the Earth. If it were at an altitude equal to twice the radius of the Earth, 2RE, how would its speed v be related to the Earth's radius RE, and the magnitude g of the acceleration due to gravity on the Earth's surface? A. v^2=(g^R(E))/9 B. v^2=2gRE C. v^2=(g^R(E))/3 D. v^2=(g^R(E))/4 E. v^2=(g^R(E)/2
Answer: C
Determine the minimum angle at which a roadbed should be banked so that a car traveling at 20.0 m/s can safely negotiate the curve if the radius of the curve is 2.00 ´ 102 m. A. 0.200° B. 0.581° C. 11.5° D. 19.6° E. 78.2°
Answer: C
What happens when a spinning ice skater draws in her outstretched arms? A. Her angular momentum decreases. B. Her angular momentum increases. C. Her moment of inertia decreases causing her to speed up. D. Her moment of inertia decreases causing her to slow down. E. The torque that she exerts increases her moment of inertia.
Answer: C
A 1000-kg car travels along a straight 500-m portion of highway (from A to B) at a constant speed of 10 m/s. At B, the car encounters an unbanked curve of radius 50 m. The car follows the road from B to C traveling at a constant speed of 10 m/s while the direction of the car changes from east to south. R-1 Ref 5-2 What is the magnitude of the frictional force between the tires and the road as the car negotiates the curve from B to C? A. 20 000 N B. 10 000 N C. 5000 N D. 2000 N E. 1000 N
Answer: D
A boy is whirling a stone around his head by means of a string. The string makes one complete revolution every second, and the tension in the string is FT. The boy then speeds up the stone, keeping the radius of the circle unchanged, so that the string makes two complete revolutions every second. What happens to the tension in the sting? A. The tension is unchanged. B. The tension reduces to half of its original value. C. The tension increases to twice its original value. D. The tension increases to four times its original value. E. The tension reduces to one-fourth of its original value.
Answer: D
A child standing on the edge of a freely spinning merry-go-round moves quickly to the center. Which one of the following statements is necessarily true concerning this event and why? O A. The angular speed of the system decreases because the moment of inertia of the system has increased. O B. The angular speed of the system increases because the moment of inertia of the system has increased. O C. The angular speed of the system decreases because the moment of inertia of the system has decreased. O D. The angular speed of the system increases because the moment of inertia of the system has decreased. O E. The angular speed of the system remains the same because the net torque on the merry-go-round is zero newton • meters.
Answer: D
A rigid body rotates about a fixed axis with a constant angular acceleration. Which one of the following statements is true concerning the tangential acceleration of any point on the body? A. Its magnitude is zero m/s2. B. It depends on the angular velocity. C. It is equal to the centripetal acceleration. D. It is constant in both magnitude and direction. E. It depends on the change in the angular velocity.
Answer: D
A rock is whirled on the end of a string in a horizontal circle of radius R with a constant period T. If the radius of the circle is reduced to R/2, while the period remains T, what happens to the centripetal acceleration of the rock? A. It remains the same. B. It increases by a factor of 2. C. It increases by a factor of 4. D. It decreases by a factor of 2. E. It decreases by a factor of 4.
Answer: D
A satellite is placed in a circular orbit to observe the surface of Mars from an altitude of 144 km. The equatorial radius of Mars is 3397 km. If the speed of the satellite is 3480 m/s, what is the magnitude of the centripetal acceleration of the satellite? A. 2.17 m/s^2 B. 2.60 m/s^2 C. 2.99 m/s^2 D. 3.42 m/s^2 E. 4.05 m/s^2
Answer: D
A solid cylinder with a mass m and radius r is mounted so that it can be rotated about an axis that passes through the center of both ends. At what angular speed w must the cylinder rotate to have the same total kinetic energy that it would have if it were moving horizontally with a speed v without rotation? A. w=v/r B. w=v^2/r^2 C. w= v/(2r) D. w= v/r *sqrt(2) E. w=v^2/(2r)
Answer: D
A spinning star begins to collapse under its own gravitational pull. Which one of the following occurs as the star becomes smaller? A. Its angular velocity decreases. B. Its angular momentum increases. C. Its angular velocity remains constant. D. Its angular momentum remains constant. E. Both its angular momentum and its angular velocity remain constant.
Answer: D
Complete the following statement: A body is in translational equilibrium A. only if it is at rest. B. only if it is moving with constant velocity. C. only if it is moving with constant acceleration. D. if it is either at rest or moving with constant velocity. E. if it is moving with either constant velocity or constant acceleration.
Answer: D
The second hand on a watch has a length of 4.50 mm and makes one revolution in 60.00 s. What is the speed of the end of the second hand as it moves in uniform circular motion? A. 9.42 ´ 10-4 m/s B. 2.67 ´ 10-3 m/s C. 5.34 ´ 10-3 m/s D. 4.71 ´ 10-4 m/s E. 2.36 ´ 10-5 m/s
Answer: D
Two points are located on a rigid wheel that is rotating with a decreasing angular velocity about a fixed axis. Point A is located on the rim of the wheel and point B is halfway between the rim and the axis. Which one of the following statements is true concerning this situation? A. Both points have the same centripetal acceleration. B. Both points have the same tangential acceleration. C. The angular velocity at point A is greater than that of point B. D. Both points have the same instantaneous angular velocity. E. Each second, point A turns through a greater angle than point B.
Answer: D
Which equation is valid only when the angular measure is expressed in radians? A. a= (change in w)/(change in t) B. w= (change in 0)/ ( change in t) C. w^2=wo^2+2a0 D. w= (vt)/r E. 0= .5 a*t^2 + wo*t
Answer: D
Which expression determines the minimum speed that the car must have at the top of the track if it is to remain in contact with the track? A. v = MgR B. v = 2gR C. v2 = 2gR D. v2 = gR E. v = gR
Answer: D
A 0.25-kg ball attached to a string is rotating in a horizontal circle of radius 0.5 m. If the ball revolves twice every second, what is the tension in the sting? A. 2 N B. 5 N C. 7 N D. 10 N E. 20 N
Answer: E
A 1000-kg car travels along a straight 500-m portion of highway (from A to B) at a constant speed of 10 m/s. At B, the car encounters an unbanked curve of radius 50 m. The car follows the road from B to C traveling at a constant speed of 10 m/s while the direction of the car changes from east to south. R-1 Ref 5-2 What is the magnitude of the acceleration of the car as it travels from A to B? A. 2 m/s^2 B. 5 m/s^2 C. 10 m/s^2 D. 20 m/s^2 E. zero m/s^2
Answer: E
A ball is whirled on the end of a string in a horizontal circle of radius R at constant speed v. The centripetal acceleration of the ball can be increased by a factor of 4 by A. keeping the speed fixed and increasing the radius by a factor of 4. B. keeping the radius fixed and increasing the speed by a factor of 4. C. keeping the radius fixed and increasing the period by a factor of 4. D. keeping the radius fixed and decreasing the period by a factor of 4. E. keeping the speed fixed and decreasing the radius by a factor of 4.
Answer: E
A compact disc rotates about its center at constant angular speed. Which one of the following quantities is constant and non-zero for a dust particle near the edge of the disc? O A. linear velocity O B. torque about the center of the disc O C. centripetal acceleration O D. angular acceleration O E. angular momentum
Answer: E
A satellite in orbit around the earth has a period of one hour. An identical satellite is placed in an orbit having a radius that is nine times larger than the first satellite. What is the period of the second satellite? A. 0.04 h B. 3 h C. 4 h D. 9 h E. 27 h
Answer: E
Approximately one billion years ago, the Moon orbited the Earth much closer than it does today. The radius of the orbit was only 24 400 km. Today, the radius is 385 000 km. The orbital period was only 23 400 s. The present period is 2.36 ´ 106 s. Assume that the orbit of the Moon is circular. Calculate the ratio of the speed of the Moon in its ancient orbit to the speed that it has today. A. 15.8 B. 12.8 C. 10.2 D. 7.15 E. 6.39
Answer: E
Complete the following statement: When a net torque is applied to a rigid object, it always produces a A. constant acceleration. B. rotational equilibrium. C. constant angular velocity. D. constant angular momentum. E. change in angular velocity.
Answer: E
The earth exerts the necessary centripetal force on an orbiting satellite to keep it moving in a circle at constant speed. Which statement best explains why the speed of the satellite does not change even though there is a net force exerted on it? A. The satellite is in equilibrium. B. The acceleration of the satellite is 0 m/s^2. C. The centripetal force has magnitude mv^2/r. D. The centripetal force is canceled by the reaction force. E. The centripetal force is always perpendicular to the velocity.
Answer: E
The maximum speed at which a car can safely negotiate an unbanked curve depends on all of the following factors except A. the diameter of the curve. B. the acceleration due to gravity. C. the coefficient of static friction between the road and the tires. D. the coefficient of kinetic friction between the road and the tires. E. the ratio of the static frictional force between the road and the tires and the normal force exerted on the car.
Answer: E
The world's largest Ferris wheel with a radius of 50.0 m is located in Yokohama City, Japan. Each of the sixty gondolas on the wheel takes 1.00 minute to complete one revolution when it is running at full speed. Note: Ignore gravitational effects. What is the uniform speed of a gondola when the Ferris wheel is running at full speed? A. 314 m/s B. 1.67 m/s C. 10.5 m/s D. 18.6 m/s E. 5.24 m/s
Answer: E
Which force is responsible for holding a car in a frictionless banked curve? A. the reaction force to the car's weight B. the vertical component of the car's weight C. the vertical component of the normal force D. the horizontal component of the car's weight E. the horizontal component of the normal force
Answer: E
Which one of the following statements most accurately describes the center of gravity of an object? A. It is the point where gravity acts on the object. B. It is the point where all the mass is concentrated. C. It must be experimentally determined for all objects. D. It is the point on the object where all the weight is concentrated. E. It is the point from which the torque produced by the weight of the object can be calculated.
Answer: E
Which statement concerning a wheel undergoing rolling motion is true? A. The angular acceleration of the wheel must be zero m/s2. B. The tangential velocity is the same for all points on the wheel. C. The linear velocity for all points on the rim of the wheel is non-zero. D. The tangential velocity is the same for all points on the rim of the wheel. E. There is no slipping at the point where the wheel touches the surface on which it is rolling.
Answer: E
