Physics 150 Exam I Test Bank Fall 2002

Multiple Choice

___ . The displacement-time graph shown at right indicates an object which
(A) is moving at constant velocity in the positive direction, which then accelerates in the opposite direction, coming to rest.
(B) is initially stationary, then begins accelerating in the negative direction.
(C) is initially moving at constant velocity, and then accelerates in the positive direction..
(D) is at rest at all times.
(E) none of the above. /
___ . The displacement-time graph shown at right indicates an object which
(A) is moving at constant velocity in the negative direction, which then accelerates in the opposite direction, coming to rest.
(B) is moving at constant velocity in the positive direction, which then accelerates in the opposite direction, coming to rest.
(C) is initially stationary, then begins accelerating in the negative direction.
(D) is initially stationary, then begins accelerating in the positive direction.
(E) none of the above. /
___ . The velocity-time graph shown at right indicates an object which
(A) is moving at constant velocity in the positive direction, which then accelerates in the opposite direction, coming to rest.
(B) is initially stationary, then begins accelerating in the negative direction.
(C) is initially moving at constant velocity, and then accelerates in the positive direction..
(D) is at rest at all times.
(E) none of the above. /

___ . The acceleration of a stone thrown upward is

(A) greater than that if a stone thrown downward.

(B) the same as that of a stone thrown downward.

(D) zero until it reaches the highest point in its motion.

(E) none of the above.

___ . If an object moving at constant velocity were to have twice its original speed, then

(A) the time it takes to cover a given distance would be doubled.

(B) the time it takes to cover a given distance would be halved.

(D) it will undergo spontaneously combustion.

(E) none of the above.

___ . If an object with no acceleration had twice its original speed,

(A) the time it takes to cover a given distance is doubled.

(B) the time it takes to cover a given distance is halved.

(D) it will undergo spontaneously combustion.

(E) none of the above.

___ . The difference between a vector and a scalar is that

(A) a vector only has direction while a scalar has magnitude and direction.

(B) a vector is just a number while a scalar has magnitude and direction.

(D) a scalar is just a number while a vector has magnitude and direction.

(E) vectors are physical quantities, while scalars are abstract quantities.

___ . If the constant speed of an object is halved

(A) the time it takes to cover a given distance is doubled.

(B) the time it takes to cover a given distance is halved.

(D) it will undergo spontaneously combustion.

(E) none of the above.

___ . A mozzarella cheese ball and a (much heavier) meat ball are both dropped from the top of the Leaning Tower of Pizza (no relation to the Tower of Pisa). If air resistance can be ignored, then

(A) the heavier ball will hit the ground before the lighter ball.

(B) the heavier ball will hit the ground after the lighter ball.

(D) more detailed information is required.

(E) none of the above.

___ . If a ball is thrown straight up from a roof at the same instant another ball is thrown downward from the same location with the same speed, then

(A) the ball thrown upward will have a greater acceleration than the other ball.

(B) the ball thrown downward will have a greater acceleration than the other ball.

(D) both balls will have the same acceleration.

(E) none of the above.

___ . Ball A thrown horizontally, and ball B is dropped from the same height at the same time. Then

(A) ball A will reach the ground first.

(B) ball B reach will reach the ground first.

(D) whichever ball is lighter ball will reach the ground first.

(E) none of the above.

___ . A fearless hunter takes aim directly at a monkey hanging from a tree branch. At exactly the instant he fires the gun, the monkey lets go of the branch. The bullet

(A) passes harmlessly over the falling monkey.

(B) is affected by gravity in the same way as the falling monkey, and so strikes the monkey.

(D) more details are required to determine what will happen.

___ . An object fired at a certain speed at an angle of 20° above the horizon will have the same range at an angle of

(A) 110°.

(B) 90°.

(D) 65°.

(E) no other angle will have the same range.

___ . If we subtract to vectors C = A -B, the reversed difference B - A is

(A) not a vector.

(B) the same result.

(D) a vector perpendicular to the first result.

(E) zero.

___ . Two vectors V1 and V2 are shown at right. The vector which most closely represents the vector sum V1 + V2 is

(E) None of the above /
___ . Two vectors V1 and V2 are shown at right. The vector which most closely represents the vector difference V1 - V2 is

(E) None of the above /

___ . If three forces (which are vectors), each of magnitude 10 N, act on the same object. The maximum and minimum force they could exert on the object (obtained by determining the magnitude of the sum of three vectors) would be

(A) 10 N and 0 N respectively.

(B) 20 N and 0 N respectively.

(D) 30 N and 0 N respectively.

(E) 30 N for both, since 10 + 10 + 10 = 30.

___ . The mass of an object

(A) is the quantity of matter it contains.

(B) is a measure of its inertia.

(D) all of the above.

(E) none of the above.

___ . The weight of an object

(A) is the quantity of matter it contains.

(B) is a measure of its inertia.

(D) is the force with which it is attracted to the earth.

(E) none of the above.

___ . If the acceleration of an object with a fixed mass is halved, then the force must have been

(A) doubled.

(B) constant.

(D) quartered.

(E) changed unpredictably.

___ . If the mass of an object is halved and force is the same, then the acceleration is

(A) the same.

(B) doubled.

(D) quadrupled.

(E) none of the above.

___ . If the same force is applied to two objects, the second with twice the mass of the first, then the acceleration of the second mass (as compared with the first) is

(A) twice.

(B) the same.

(D) quartered.

(E) changed unpredictably.

___ . If the mass of an object is halved, then the force required to maintain the same acceleration is

(A) the same.

(B) doubled.

(D) quadrupled.

(E) none of the above.

___ . To keep an object in motion at constant speed (against kinetic friction) is usually

(A) no force.

(B) less force than required to start the object moving (overcoming static friction).

(D) more force than required to start the object moving (overcoming static friction).

(E) none of the above.

___ . To start an object in motion (against static friction) is usually

(A) no force.

(B) less force than required to keep the object moving (overcoming kinetic friction).

(D) more force than required to keep the object moving (overcoming kinetic friction).

(E) none of the above.

___ . For an object in motion, the acceleration a and the velocity v

(A) are always in the same direction.

(B) may either be in the same direction or in opposite directions.

(D) must be perpendicular.

(E) are not vectors, and so any discussion of direction is irrelevant.

___ . Ball A thrown horizontally, and ball B is dropped from the same height at the same time. Then

(A) ball A will reach the ground first.

(B) ball B reach will reach the ground first.

(D) which ever ball is heavier will reach the ground first.

(E) none of the above.

___ . As Dr. Gallis sits on a table in the front of the room (in equilibrium), the force that the table exerts on Dr. Gallis is

(A) less than the force that Dr. Gallis exerts on the table.

(B) equal to the force that Dr. Gallis exerts on the table.

(E) none of the above.

___ . As Dr. Gallis hauls the computer cart to the front of the room (accelerating the cart), the force that the cart exerts on Dr. Gallis is

(A) less than the force that Dr. Gallis exerts on the cart.

(B) equal to the force that Dr. Gallis exerts on the cart.

(D) definitely zero, definitely.

(E) none of the above.

___ . The normal force exerted by a surface on an object

(A) is always equal to the objects weight.

(B) is caused to the friction between the surface and the object’s surface.

(D) all of the above.

(E) none of the above.

Mini Matching (1 point each) The free body diagram at right illustrates a block being pulled up an inclined surface. Identify the forces on the block below by the letter indicated in the diagram
___ T, the tension in the rope
___ W, the weight of the block
___ FN, the normal force
___ Ff, the force of friction /
Mini Matching (1 point each) The free body diagram at right illustrates a block being pulled across a horizontal surface. Identify the forces on the block below by the letter indicated in the diagram
___ Ff, the force of friction
___ FN, the normal force
___ W, the weight of the block
___ T, the tension in the rope /

Problems

A certain graceful physics professor initially moving at 5 m/s across the front of the room comes to rest in a distance of 1m (after colliding with a certain waste paper basket).

(a) What is his acceleration (take the initial direction of his motion as the “positive direction”)?

(b) How much time did it take him to “put on the brakes” and come to rest?

Mark McGwire swings at a 40 m/s pitch, sending it in the opposite direction at 60m/s with an impact lasting 5.00E-3s (5 milliseconds).

(a) What is the acceleration of the ball?

(b) What is the net displacement (change in position)of the ball during the impact?

Dr. Gallis’s Lawnmower has an acceleration of .200 m/s2. He starts from rest and covers a distance of 5m.

(a) What is his speed after covering this distance?

(b) How much time did it take him to cover this distance?

An object is dropped from the top of a tall building, and hits the street 5.00 s later.

(A) How high is the building?

(B) How fast is the object moving as it hits the street?

A blunderbuss (a primitive canon) can fire a slug 100m vertically upward.

(a) What is the speed of the slug as it is fired from the blunderbuss?

(b) What is the maximum range the blunderbuss can throw a slug?

A beloved coffee mug slides (horizontally) off of a 1m high lab bench, and lands (mercifully intact) on the ground 2m away .

(A) How long does it take the mug to hit the ground?

(B) What is the final vertical component of velocity?

(D) How far from the table did the mug land?

A water balloon is flung (hey, it’s a projectile!) horizontally from the roof of a building 20.0 m high with an initial speed of 10.0 m/s.

(A) How long does it take the balloon to hit the ground?

(B) What is the final vertical component of velocity?

(D) How far from the building did the balloon land?

A water balloon is flung horizontally from the roof of a building 30.0 m high with an initial speed of 20.0 m/s.

(a) How long does it take the balloon to hit the ground?

(b) What is the final vertical component of velocity?

(d) How far from the building did the balloon land?

Block A (mass = 4.00 kg) and Block B (mass = 8.00 kg) are suspended by a string on either side of a friction-less pulley. Since they are tied together (interacting through the tension in the string) they will accelerate at the same rate.