Physics Exam 2 Concept Questions

If two forces of equal magnitude act on an object that is hinged at the pivot, the force acting farther from the pivot must produce the greater torque about the pivot. A) True. B) False. C) Unable to decide without knowing the shape of the object.

B) False.

A stock person at the local grocery store has a job consisting of the following 5 segments: (1) pickup up boxes of tomatoes from the stockroom floor (2) accelerating to a comfortable speed (3) carrying the boxes to the tomato display at a constant speed (4) decelerating to a stop (5) lowering the boxes slowly to the floor. During which of the 5 segments of the job does the stock person do positive work on the boxes?

(1) and (2)

If an irregularly shaped object (such as a wrench) is dropped from rest in a classroom and feels no air resistance, it will accelerate ... A) But it will not spin. B) And turn until its center of gravity reaches its lowest point. C) And turn about its center of gravity with uniform angular speed. D) And turn about its center of gravity with uniform angular acceleration. E) And spin until its center of gravity reaches its highest point

A) But it will not spin.

You are standing on a skateboard, initially at rest. A friend throws a very heavy ball towards you. You can either catch the object or deflect the object back towards your friends (such that it moves away from you with the same speed as it was originally thrown). What should you do in order to MINIMIZE your speed on the skateboard? A) Catch the ball. B) Deflect the ball. C) Your final speed on the skateboard will be the same regardless whether you catch the ball or deflect the ball

A) Catch the ball.

A 1.0 kg block and a 2.0 kg block are pressed together on a horizontal frictionless surface with a compressed very light spring between them. They are not attached to the spring. After they are released and both have moved free of the spring ... A) The lighter block will have more kinetic energy than the heavier block. B) The heavier block will have more kinetic energy than the lighter block C) Both blocks will have the same amount of kinetic energy. D) The magnitude of the momentum of the heavier block will be greater than the magnitude of the momentum of the lighter block. E) Both blocks will have equal speeds

A) The lighter block will have more kinetic energy than we have the heavier block.

A ball drops some distance & gains 30J of kinetic energy. do NOT ignore air resistance. How much gravitational potential energy did the ball lose? A) more than 30 J B) exactly 30 J C) less than 30 J

A) more than 30 J

A box of mass m is pressed against (but is not attached to) an ideal spring of force constant k and negligible mass, compressing the spring a distance x. After it is released, the box slides up a frictionless incline as shown in the figure & eventually stops. If we repeat this experiment with a box of mass 2m ... (pic for #12) A) the lighter box will go twice as high up the incline as the heavier box B) just as it moves free of the spring, the lighter box will be moving twice as fast as the heavier box C) both boxes will have the same speed D) both boxes will reach the same maximum height on the incline

A) the lighter box will go twice as high up the incline as the heavier box

An object is moving forward with a constant velocity. Which statement about this object MUST be true? A) the net force on the object is zero B) the net force on the object is in the forward direction C) no forces are acting on the object D) the acceleration of the object is in the forward direction

A) the net force on the object is zero

when an object is solely under the influence of conservative forces, the sum of its kinetic and potential energies does not change A) true B) false

A) true

If the dot product of two nonzero vectors is zero, the vectors must be perpendicular to each other. A. True B. False

A. True

As a tile falls from the roof of a building to the ground its momentum is conserved. A) True B) False

B) False

If all the components of a vector are equal to 1, then that vector is a unit vector A) True B) False

B) False

There must be equal amounts of mass on both sides of the center of mass of an object A) True B) false

B) False

A horizontal disk rotates about a vertical axis through its center. Point P is midway between the center and the rim of the disk, and point Q is on the rim. If the disc turns with constant angular velocity, which of the following statements about it are true? (There may be more than one correct choice) A) P and Q have the same linear acceleration. B) Q is moving twice as fast as P. C) The linear acceleration of Q is twice as great as the linear acceleration of P. D) The linear acceleration of P is twice as great as the linear acceleration of Q. E) The angular velocity of Q is twice as great as the angular velocity of P.

B) Q is moving twice as fast as P. C) The linear acceleration of Q is twice as great as the linear acceleration of P.

The two rotating systems shown in the figure (#35) differ only in that the two identical movable masses are positioned at different distances on the axis of rotation. If you release the hanging block simultaneously from rest, and if the ropes do not slip, which block lands first A) The block at the left lands first B) The block at the right lands first C) Both blocks land at the same time

B) The block at the right lands first

When a rigid body rotates about a fixed axis, all the points in the body have the same A) tangential speed B) angular acceleration C) tangential acceleration D) linear displacement E) centripetal acceleration

B) angular acceleration

Two identical balls are thrown directly upward, ball A at speed v and ball B at speed 2v, and they feel no air resistance. Which statement about these balls is correct? A) ball B will go twice as high as ball A because it had twice the initial speed B) ball B will go four times high as ball A because it had 4x the initial kinetic energy C) the balls will reach the same height because they have the same mass & same acceleration D) at its highest point, ball B will have twice as much gravitational potential energy as ballA because it started out moving twice as fast E) at their highest point, the acceleration of each ball is instantaneously equal to zero because they stop for an instant

B) ball B will go four times high as ball A because it had 4x the initial kinetic energy

A baseball is thrown vertically upwards and feels no air resistance. As it is rising ... A) both its momentum and its mechanical energy are conserved B) its momentum is not conserved, but its mechanical energy is conserved C) both its momentum and its kinetic energy are conserved D) it's kinetic energy is conserved, but its momentum is not conserved E) its gravitational potential energy is not conserved, but its momentum is conserved

B) its momentum is not conserved, but its mechanical energy is conserved

A box of mass m is pressed against (but is not attached to) an ideal spring of force constant k and negligible mass, compressing the spring a distance x. After it is released, the box slides up a frictionless incline as shown in the figure & eventually stops. If we repeat this experiment but instead compress the spring a distance of 2x ... (pic for #13) A) the box will go up the incline twice as high as before B) just as it moves free of the spring, the box will be traveling twice as fast as before C) just as it moves free of the spring, the box will be traveling 4x as fast as before D) just as it moves free of the spring, the box will have twice as much kinetic energy as a before E) just before it is released, the box has twice as much elastic potential energy as before

B) just as it moves free of the spring, the box will be traveling twice as fast as before

Two objects, one of mass m and the other of mass 2m, are dropped from the top of a building. When they hit the ground ... A) both of them will have the same kinetic energy B) the heavier one will have twice the kinetic energy of the lighter one C) the heavier one will have four times the kinetic energy of the lighter one D) the heavier one will have sqrt(2) times the kinetic energy of the lighter one

B) the heavier one will have twice the kinetic energy of the lighter one

If two nonzero vectors point in the same direction, their dot product must be zero. A. True B. False

B. False

The value of the dot product of two vectors depends on the particualr coordinate system being used A. True B. False

B. False

Consider a plot of the displacement (x) as a function fo the applied force (F) for an ideal elastic spring. The slope of the curve would be A. the spring constant B. reciprocal of the spring constant C. acceleration due to gravity D. reciprocal of the acceleration of gravity E. the mass of the object attached to the spring

B. reciprocal of the spring constant

A 4.0-kg object is moving with speed 2.0 m/s. A 1.0-kg object is moving with the speed 4.0 m/s. Both objects encounter the same constant braking force, and are brought to rest. Which object travels the greater distance before stopping? A) the 4.0-kg object while it is traveling down B) the 1.0-kg object upward while it is traveling down C) Both objects travel the same distance D) It is impossible to know without knowing how long each force acts

C) Both objects travel the same distance

A dumbbell shaped object is composed by 2 equal masses, and, connected by a rod of negligible mass and length r. If I1 is the moment of inertia of this object with respect to an axis passing through the center of the rod and perpendicular to it and I2 is the moment of inertia with respect to an axis passing through one of the masses, it follows that ... A) I1 = I2 B) I1 > I2 C) I1 < I2

C) I1 < I2

A small glider is coasting horizontally when suddenly a very heavy piece of cargo falls out of the bottom of the plane. You can neglect air resistance. Just after the cargo has fallen out ... A) the plane speeds up and the cargo slows down. B) the plane speeds up but the cargo does not change speed. C) Neither the cargo nor the plane change speed. D) The cargo slows down with the plane does not change speed. E) Both the cargo in the plane speed up.

C) Neither the cargo nor the plane change speed.

In a perfectly ELASTIC collision between two perfectly rigid objects ... A) The momentum of each object is conserved. B) The kinetic energy of each object is conserved. C) The momentum of the system is conserved for the kinetic energy of the system is not conserved. D) Both the momentum and the kinetic energy of the system are conserved E) The kinetic energy of the system is conserved, but the momentum of the system is not conserved

D) Both the momentum and the kinetic energy of the system are conserved

consider 2 less-than-desirable options. In the 1st you are driving 30 mph and crash head-on into an identical car also going 30 mph. In the 2nd option you are driving 30 mph and crash head-on into a stationary brick wall. In neither case does your car bounce off the thing it hits, and the collision time is the same in both cases. Which of these two situations would result in the greatest impact force? A) hitting the other car B) hitting the brick wall to a vector voltage, but greater than zero C) The force would be the same in both cases D) We cannot answer this question without more info E) None of these is true

C) The force would be the same in both cases

In a perfectly INELASTIC collision between two perfectly rigid objects ... A) The momentum of each object is conserved. B) The kinetic energy of each object is conserved. C) The momentum of the system is conserved but the kinetic energy of the system is not conserved. D) Both the momentum and the kinetic energy of the system are conserved E) The kinetic energy of the system is conserved, but the momentum of the system is not conserved

C) The momentum of the system is conserved but the kinetic energy of the system is not conserved.

A small car has a head on collision with a large truck. Which of the following statements concerning the magnitude of the average force due to the Collision is correct? A) The truck experiences the greater average force. B) The small car experience has the greater average force C) The small car and the truck experience the same average force. D) It is impossible to tell since the masses are not given E) It is impossible to tell since the velocities are not given

C) The small car and the truck experience the same average force.

Is it possible for a system to have negative potential energy? A) Yes, as long as the kinetic energy is positive B) Yes, as long as the total energy is positive C) Yes, since the choice of the zero of potential energy is arbitrary D) No, because the kinetic energy of a system must equal its potential energy E) No, because this would have no physical meaning

C) Yes, since the choice of the zero of potential energy is arbitrary

A ball drops some distance & loses 30 J of gravitational potential energy. Do NOT ignore air resistance. How much kinetic energy did the ball gain? A) more than 30 J B) exactly 30 J C) less than 30 J

C) less than 30 J

Which, if any, of the following statements concerning the work done by a conservative force is NOT true? A) it can always bee expressed as thee difference b/t thee initial & final values of a potential energy function B) it is independent of the path of ht body & depends only on the starting & ending points C) when the starting & ending points are the same, the total work is zero D) All of the above statements are true E) none of the above statements are true

D) All of the above statements are true

Two stones, one of mass m and the other of mass 2m, are thrown directly upward with the same velocity at the same time from ground level and feel no air resistance. Which statement about these stones is true? A) the heavier stone will go twice as high as the lighter one because it initially had twice as much kinetic eneregy B) Both stones will reach the same height because they initially had the same amount of kinetic energy C) At their highest point, both stones will have the same gravitational potential energy because they reach the same height D) At its highest point, the heavier stone will have twice as much gravitational potential energy as the lighter one because it is twice as heavy E) The lighter stone will reach its maximum height sooner than the heavier one

D) At its highest point, the heavier stone will have twice as much gravitational potential energy as the lighter one because it is twice as heavy

Block 1 & block 2 have the same mass, m, & are released from the top of 2 inclined planes of the same height making 30º and 60º angles with the horizontal direction, respectively. If the coefficient of friction is the same in both cases, which of the blocks is going faster when it reaches the bottom of its respective incline? A) we must know the actual masses of the blocks to answer B) both blocks have the same speed at the bottom C) block 1 is faster D) block 2 is faster E) there is not enough info to answer the question b/c we do not know the value of the coefficient of kinetic friction

D) block 2 is faster

Two men, Joel and Jerry, push against a wall. Jerry stops after 10 min, while Joel is able to push for 5.0 min longer. Compare the work they do. A) Both men do positive work, but Joel does 75% more work than Jerry B) both men do positive work, but Joel dose 50% more work than Jerry C) Both men do positive work, but Jerry does 50% more work than Joel D) Both men do positive work, but Joel does 25% more work than Jerry E) Neither of them does any work

E) Neither of them does any work