Concept questions physics

(Ch6) Complete the following statement: Work may be expressed using all of the following units except A) N ⋅ m. B) joule. C) erg. D) ft ⋅ lb. E)watt.

E) watt.

(Ch7) An object of mass 3m, initially at rest, explodes breaking into two fragments of mass m and 2m, respectively. Which one of the following statements concerning the fragments after the explosion is true? A) They will fly off at right angles. B) They will fly off in the same direction. C) The smaller fragment will have twice the speed of the larger fragment. D) The larger fragment will have twice the speed of the smaller fragment. E) The smaller fragment will have four times the speed of the larger fragment.

C) The smaller fragment will have twice the speed of the larger fragment.

(Ch6) Which one of the following situations is an example of an object with a non-zero kinetic energy? A) a drum of diesel fuel on a parked truck B) a stationary pendulum C) a satellite in geosynchronous orbit D) a car parked at the top of a hill E) a boulder resting at the bottom of a cliff

C) a satellite in geosynchronous orbit

(Ch5) A solar-powered car is traveling at constant speed around a circular track. What happens to the centripetal acceleration of the car if the speed is doubled? A) The centripetal acceleration remains the same. B) The centripetal acceleration increases by a factor of 2. C) The centripetal acceleration increases by a factor of 4. D) The centripetal acceleration is decreased by a factor of one-half. E) The centripetal acceleration is decreased by a factor of one-fourth.

C. The centripetal acceleration increases by a factor of 4.

(Ch7) A tennis ball has a velocity of 12 m/s downward just before it strikes the ground and bounces up with a velocity of 12 m/s upward. Which statement is true concerning this situation? A) The momentum of the ball and the momentum of the earth both change. B) Neither the momentum of the ball nor the momentum of the earth changes. C) The momentum of the ball is changed; and the momentum of the earth is not changed. D) The momentum of the ball is unchanged; and the momentum of the earth is changed. E) Both the momentum and the kinetic energy of the ball change because of the collision.

A) The momentum of the ball and the momentum of the earth both change.

(Ch7) A space vehicle of mass m has a speed v. At some instant, it separates into two pieces, each of mass 0.5m. One of the pieces is at rest just after the separation. (Ch7) 55. Which one of the following statements concerning this situation is true? A) The moving piece has speed 2v. B) This process conserves kinetic energy. C) The piece at rest possesses kinetic energy. D) The process does not conserve total energy. E) This process does not conserve momentum. (Ch7) 56. What is the kinetic energy of the moving piece just after the separation? A) zero joules B) C) D) mv2 E) 2mv2

A) The moving piece has speed 2v. D) mv2

(Ch7) A rock is dropped from a high tower and falls freely under the influence of gravity. Which one of the following statements concerning the rock as it falls is true? Neglect the effects of air resistance. A) The rock will gain an equal amount of momentum during each second. B) The rock will gain an equal amount of kinetic energy during each second. C) The rock will gain an equal amount of speed for each meter through which it falls. D) The rock will gain an equal amount of momentum for each meter through which it falls. E) The amount of momentum the rock gains will be proportional to the amount of potential energy that it loses.

A) The rock will gain an equal amount of momentum during each second

(Ch5) A 1500-kg vehicle travels at a constant speed of 22 m/s around a circular track that has a radius of 85 m. Which statement is true concerning this vehicle? A) The velocity of the vehicle is changing. B) The vehicle is characterized by constant velocity. C) The vehicle is characterized by constant acceleration. D) The vehicle has a velocity vector that points along the radius of the circle. E)The vehicle has an acceleration vector that is tangent to the circle at all times

A) The velocity of the vehicle is changing.

(Ch7) Complete the following statement: Different types of collisions between interacting bodies are categorized on the basis of A) kinetic energy conservation. B) mechanical energy conservation. C) linear momentum conservation. D) the magnitude of the forces involved. E)the temporal duration of the collision

A) kinetic energy conservation.

(Ch5) The radius of Saturn's orbit around the Sun is about 10 times that of Earth. Complete the following statement: The period of Saturn is about A) 10 years. B) 30 years. C) 40 years. D) 90 years. E) 160 years.

B) 30 years.

(Ch6) In which one of the following situations will there be an increase in kinetic energy? A) A projectile approaches its maximum height. B) A ball starts from rest and freely rolls downhill. C) A box is pulled across a rough floor at constant speed. D) A satellite travels in a circular orbit around the earth at fixed altitude. E) A stone at the end of a string is whirled in a horizontal circle at constant speed.

B) A ball starts from rest and freely rolls downhill.

(ch 8) A long thin rod of length 2L rotates with a constant angular acceleration of 8.0 rad/s2 about an axis that is perpendicular to the rod and passes through its center. (ch 8) 46. 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 (ch 8) 47. 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 (ch 8) 48. 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 (ch 8) 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

C) 2:1 C) 2:1 A) 1:1 C) 2:1

(ch 8) A circular hula hoop rolls upright without slipping on a flat horizontal surface. Which one of the following statements 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.

C) Every point on the rim of the wheel has a different velocity.

(Ch6) Which one of the following statements concerning kinetic energy is true? A) Kinetic energy can be measured in watts. B) Kinetic energy is always equal to the potential energy. C) Kinetic energy is always positive. D) Kinetic energy is a quantitative measure of inertia. E) Kinetic energy is directly proportional to velocity.

C) Kinetic energy is always positive

(Ch5) 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.

C) The spaceship is in free fall and its floor cannot press upwards on the astronauts.

(Ch6) Which one of the following choices is an example of a non-conservative force? A) gravitational force B) electrical force C) kinetic frictional force D) elastic spring force

C) kinetic frictional force

(ch 8) A car is moving along a horizontal road at a constant velocity that is directed 45° south of east. What is the direction of the angular velocity of the wheels of the car? A) 45° south of west B) 45° north of west C) 45° south of east D) 45° north of east E) due east

D) 45° north of east

(Ch5) 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

D) 8 years

.(Ch6) In which one of the following situations is zero net work done? A) A ball rolls down an inclined plane. B) A physics student stretches a spring. C) A projectile falls toward the surface of Earth. D) A box is pulled across a rough floor at constant velocity. E)A child pulls a toy across a rough surface causing it to accelerate.

D) A box is pulled across a rough floor at constant velocity.

(Ch7) 29. Which one of the following is characteristic of an inelastic collision? A) Total mass is not conserved. B) Total energy is not conserved. C) Linear momentum is not conserved. D) Kinetic energy is not conserved. E) The change in momentum is less than the total impulse.

D) Kinetic energy is not conserved.

(Ch5) 19. Complete the following statement: 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.

A) the mass of the car.

(ch 8) 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) upward B) downward C) left D) right E) into the paper

A) upward

(Ch7) A sled of mass m is coasting on the icy surface of a frozen river. While it is passing under a bridge, a package of equal mass m is dropped straight down and lands on the sled (without causing any damage). The sled plus the added load then continue along the original line of motion. How does the kinetic energy of the (sled + load) compare with the original kinetic energy of the sled? A) It is 1/4 the original kinetic energy of the sled. B) It is 1/2 the original kinetic energy of the sled. C) It is 3/4 the original kinetic energy of the sled. D) It is the same as the original kinetic energy of the sled. E) It is twice the original kinetic energy of the sled.

B) It is 1/2 the original kinetic energy of the sled.

(Ch6) A block is dropped from a high tower and is falling freely under the influence of gravity. Which one of the following statements is true concerning this situation? Neglect air resistance. A) As the block falls, the net work done by all of the forces acting on the block is zero joules. B) The kinetic energy increases by equal amounts over equal distances. C) The kinetic energy of the block increases by equal amounts in equal times. D) The potential energy of the block decreases by equal amounts in equal times. E) The total energy of the block increases by equal amounts over equal distances.

B) The kinetic energy increases by equal amounts over equal distances.

(Ch7) Two objects constitute an isolated system. In an elastic collision between the two objects, which one of the following statements is a false statement? A) The total kinetic energy is conserved. B) The kinetic energy of each object is the same before and after the collision. C) The total momentum is conserved. D) The magnitude of the force exerted by each object on the other object is equal. E) The total kinetic energy before the collision is equal to the total kinetic energy after the collision.

B) The kinetic energy of each object is the same before and after the collision.

(Ch6) Two balls of equal size are dropped from the same height from the roof of a building. One ball has twice the mass of the other. When the balls reach the ground, how do the kinetic energies of the two balls compare? A) The lighter one has one fourth as much kinetic energy as the other does. B) The lighter one has one half as much kinetic energy as the other does. C) The lighter one has the same kinetic energy as the other does. D) The lighter one has twice as much kinetic energy as the other does. E) The lighter one has four times as much kinetic energy as the other does.

B) The lighter one has one half as much kinetic energy as the other does.

(Ch6) In which one of the following systems is there a decrease in gravitational potential energy? A) a boy stretches a horizontal spring B) a girl jumps down from a bed C) a crate rests at the bottom of an inclined plane D) a car ascends a steep hill E) water is forced upward through a pipe

B) a girl jumps down from a bed

(ch 8) A satellite follows a circular path with constant speed around a planet. Which one of the following quantities is constant and non-zero for this satellite? A) linear velocity B) angular velocity C) centripetal acceleration D) angular acceleration E) total acceleration

B) angular velocity

(Ch5) 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

B) the force of friction

(ch 8) Two points are located on a rigid wheel that is rotating with 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 concerning this situation is true? 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.

D) Both points have the same instantaneous angular velocity.

(Ch5) 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/3, while the period remains T, what happens to the centripetal acceleration of the rock? A) The centripetal acceleration remains the same. B) The centripetal acceleration increases by a factor of 3. C) The centripetal acceleration increases by a factor of 9. D) The centripetal acceleration decreases by a factor of 3. E) The centripetal acceleration decreases by a factor of 9.

D) The centripetal acceleration decreases by a factor of 3.

(Ch6) A rock is thrown straight up from the surface of the Earth. Which one of the following statements describes the energy transformation of the rock as it rises? Neglect air resistance. A) The total energy of the rock increases. B) The kinetic energy increases and the potential energy decreases. C) Both the potential energy and the total energy of the rock increase. D) The kinetic energy decreases and the potential energy increases. E) Both the kinetic energy and the potential energy of the rock remain the same.

D) The kinetic energy decreases and the potential energy increases.

(Ch5) A boy is whirling a stone around his head by means of a string. The string makes one complete revolution every second; and the magnitude of the tension in the string is F. 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 magnitude of the tension is unchanged. B) The magnitude of the tension reduces to half of its original value, F/2. C) The magnitude of the tension increases to twice its original value, 2F. D) The magnitude of the tension increases to four times its original value, 4F. E) The magnitude of the tension reduces to one-fourth of its original value, F/4.

D) The magnitude of the tension increases to four times its original value, 4F.

(Ch7) A stationary bomb explodes in space breaking into a number of small fragments. At the location of the explosion, the net force due to gravity is zero newtons. Which one of the following statements concerning this event is true? A) Kinetic energy is conserved in this process. B) All of the fragments must have equal kinetic energies. C) The sum of the kinetic energies of the fragments must be zero. D) The vector sum of the linear momenta of the fragments must be zero. E) The mass of any one fragment must be equal to the mass of any other fragment.

D) The vector sum of the linear momenta of the fragments must be zero.

(Ch5) Complete the following statement: 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.

D) the coefficient of kinetic friction between the road and the tires

(Ch6) Which one of the following has the largest kinetic energy? A) a raindrop falling B) a woman swimming C) a jet airplane flying at its maximum speed D) the earth moving in its orbit around the sun E) the space shuttle orbiting the Earth

D) the earth moving in its orbit around the sun

(Ch7) Complete the following statement: Momentum will be conserved in a two-body collision only if A) both bodies come to rest. B) the collision is perfectly elastic. C) the kinetic energy of the system is conserved. D) the net external force acting on the two-body system is zero. E) the internal forces of the two body system cancel in action-reaction pairs.

D) the net external force acting on the two-body system is zero.

(Ch6) Complete the following statement: A force that acts on an object is said to be conservative if A) it obeys Newton's laws of motion. B) it results in a change in the object's kinetic energy. C) it always acts in the direction of motion of the object. D) the work it does on the object is independent of the path of the motion. E) the work it does on the object is equal to the increase in the object's kinetic energy.

D) the work it does on the object is independent of the path of the motion.

(Ch6) Which one of the following is not a unit of energy? A) foot ⋅ pound B) kilowatt ⋅ hour C) newton ⋅ meter D) watt E) joule

D) watt

(Ch7) In which one of the following situations is linear momentum not conserved? A) A bomb suspended by a string explodes into one hundred fragments. B) A bowling ball collides with a set of ten pins. C) A golf ball is struck by a club. D) An astronaut floating in space throws a hammer away and subsequently moves in the opposite direction. E) A tree limb is struck by lightning and falls to the ground.

E) A tree limb is struck by lightning and falls to the ground.

(Ch7) Which one of the following statements concerning momentum is true? A) Momentum is a force. B) Momentum is a scalar quantity. C) The SI unit of momentum is kg ⋅ m2/s. D) The momentum of an object is always positive. E) Momentum and impulse are measured in the same units.

E) Momentum and impulse are measured in the same units.

(Ch7) A stunt person jumps from the roof of a tall building, but no injury occurs because the person lands on a large, air-filled bag. Which one of the following best describes why no injury occurs? A) The bag provides the necessary force to stop the person. B) The bag reduces the impulse to the person. C) The bag increases the amount of time the force acts on the person and reduces the change in momentum. D) The bag decreases the amount of time during which the momentum is changing and reduces the average force on the person. E) The bag increases the amount of time during which the momentum is changing and reduces the average force on the person.

E) The bag increases the amount of time during which the momentum is changing and reduces the average force on the person.

(Ch5) The Earth exerts the necessary centripetal force on an orbiting satellite to keep it moving in a circle at constant speed. Which one of the following statements best explains why the speed of the satellite does not change although there is a net force exerted on it? A) The satellite is in equilibrium. B) The acceleration of the satellite is zero m/s2. C) The centripetal force has magnitude mv2/r. D) The centripetal force is canceled by the reaction force. E) The centripetal force is always perpendicular to the velocity.

E) The centripetal force is always perpendicular to the velocity.

(Ch6) An elevator supported by a single cable descends a shaft at a constant speed. The only forces acting on the elevator are the tension in the cable and the gravitational force. Which one of the following statements is true? A) The magnitude of the work done by the tension force is larger than that done by the gravitational force. B) The magnitude of the work done by the gravitational force is larger than that done by the tension force. C) The work done by the tension force is zero joules. D) The work done by the gravitational force is zero joules. E) The net work done by the two forces is zero joules.

E) The net work done by the two forces is zero joules.

(ch 8) 24. 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) The tangential acceleration is zero m/s2. B) The tangential acceleration depends on the angular velocity. C) The tangential acceleration is equal to the centripetal acceleration. D) The tangential acceleration is constant in both magnitude and direction. E) The tangential acceleration depends on the change in the angular velocity.

E) The tangential acceleration depends on the change in the angular velocity.

(Ch7) Which one of the following statements concerning center of mass is true? A) All of an object's mass is located at its center of mass. B) The center of mass of an object must be located within the object. C) The center of mass of a system of objects cannot change even if there are forces acting on the objects. D) The velocity of the center of mass of a system of objects is greatly affected by a collision of objects within the system. E) The velocity of the center of mass of a system of objects is constant when the sum of the external forces acting on the system is zero.

E) The velocity of the center of mass of a system of objects is constant when the sum of the external forces acting on the system is zero.

(Ch6) A donkey pulls a crate up a rough, inclined plane at constant speed. Which one of the following statements concerning this situation is false? A) The gravitational potential energy of the crate is increasing. B) The net work done by all the forces acting on the crate is zero joules. C) The work done on the crate by the normal force of the plane is zero joules. D) The donkey does "positive" work in pulling the crate up the incline. E) The work done on the object by gravity is zero joules.

E) The work done on the object by gravity is zero joules.

(Ch7) Two objects of equal mass traveling toward each other with equal speeds undergo a head on collision. Which one of the following statements concerning their velocities after the collision is necessarily true? A) They will exchange velocities. B) Their velocities will be reduced. C) Their velocities will be unchanged. D) Their velocities will be zero. E) Their velocities may be zero.

E) Their velocities may be zero.

(ch 8) Which one of the following statements 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.

E) There is no slipping at the point where the wheel touches the surface on which it is rolling.

(Ch6) Which one of the following choices is an example of a conservative force? A) tension B) normal force C) static frictional force D) motor propulsion force E) elastic spring force

E) elastic spring force

(Ch5) 16. 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

E) the horizontal component of the normal force

(Ch7) Complete the following statement: A collision is elastic if A) the final velocities are zero. B) the objects stick together. C) the final kinetic energy is zero. D) the final momentum is zero. E) the total kinetic energy is conserved.

E) the total kinetic energy is conserved.

(Ch5) A ball is whirled on the end of a string in a horizontal circle of radius R at constant speed v. Complete the following statement: 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.

E. keeping the speed fixed and decreasing the radius by a factor of 4.