Physics 11A Review MC

C. C

A block is at rest on an inclined ramp. Which of the Free Body Diagrams below is correct? Note: the length of the vectors matters. A. A B. B C. C D. D

C. its velocity is perpendicular to the acceleration.

If I toss a ball up into the air and across a field (think general parabolic motion), when the ball is at the highest point of its trajectory A. its acceleration is zero B. the horizontal and vertical components of its velocity are zero. C. its velocity is perpendicular to the acceleration . D. its velocity and acceleration are both zero

A. at their current heights.

Two blocks with the same mass are connected by a lightweight cord that runs through an ideal pulley. They are held in the positions shown. When released, the blocks will end up A. at their current heights. B. at the same height. C. with block 1 on the ground. D. with block 2 on the ground.

E. Q has a smaller a(rad) and a smaller a(tan) than P.

A DVD is rotating with an ever-increasing speed. The point P is close to the rim, and the point Q is close to the axis of rotation of the DVD. How do the centripetal acceleration a(rad) and tangential acceleration a(tan) compare at points P and Q? A. P and Q have the same a(rad) and a(tan). B. Q has a greater a(rad) and a greater a(tan) than P. C. Q has a smaller a(rad) and a greater a(tan) than P D. Q has a greater a(rad) and a smaller a(tan) than P. E. Q has a smaller a(rad) and a smaller a(tan) than P. F. P and Q have the same a(rad), but Q has a greater a(tan) than P

6.0

A pendulum bob with a weight of 8.0 N is held at an angle θ from the vertical by a horizontal force F as shown. The tension in the string supporting the ball is 10.0 N. The horizontal force F must be _______ N (Enter ONLY the number (without the N))

C D E

A ball, hanging from the ceiling by a string, is pulled back and then released (the image below shows its position the instant before it is released). Select all statements that are true regarding the ball's FBD immediately after its release (air resistance is neglible). A. There are 3 forces present. B. There is a gravitational force pointing in the direction of motion. C. There is a tension force pointing along the string. D. There is a gravitational force pointing straight down. E. The net force points in the direction of motion. F. There is a drag force pointing in the opposite direction of motion.

C. Directly back in the hand that threw it

A bicyclist is riding at constant speed along a straight path. The rider throws a ball straight up to a height of a few meters above her head. Ignoring air resistance, where will the ball land? A. Ahead of the rider B. Behind the rider C. Directly back in the hand that threw it D. Depends on the maximum height the ball reaches

D. Gravity, a normal force, and kinetic friction

A bobsledder pushes her sled across horizontal snow to get it going, then jumps in. After she jumps in, the sled gradually slows to a halt. What forces act on the sled just after she's jumped in? A. Gravity and kinetic friction B. Gravity and a normal force C. Gravity and the force of the push D. Gravity, a normal force, and kinetic friction E. Gravity, a normal force, kinetic friction, and the force of the push

C. T > mg

A box of mass m is hung with a string from the ceiling of an elevator that is accelerating upward. Which of the following best describes the tension in the string? A. mg > T B. T = mg C. T > mg

B. Four times as big

A car goes around a curve of radius r at a constant speed v. Then it goes around the same curve at double the original speed. What is the centripetal acceleration of the car as it goes around the curve for the second time, compared to the first? A. Twice as big B. Four times as big C. The same D. Half as big E. One-fourth as big

F. 0.40 m/s^2

A car is being pulled slowly by a tow truck. The tension in the tow rope is 300N and a 200N friction force opposes the motion. With these two horizontal forces acting on the car, the car's acceleration is 0.1 m/s2. If the tension in the tow rope is increased to 600N, but the 200N friction force remains constant, what is the car's new acceleration. A. 0.05 m/s^2 B. 0.10 m/s^2 C. 0.15 m/s^2 D. 0.20 m/s^2 E. 0.30 m/s^2 F. 0.40 m/s^2 G. 0.60 m/s^2 H. 0.80 m/s^2

A. A

A car is rounding a corner on a banked curve without friction. Which one of the following shows the correct Free body diagram? A. A B. B C. C D. D E. E

C. C

A car is slowing down while driving around a curve. Which direction (A-E) shows the acceleration vector at the point P A. A B. B C. C D. D E. E

B. B

A car is traveling around a curve at a steady 45 mph. Which vector shows the direction of the car's acceleration? A. A B. B C. C D. D E. The acceleration is zero.

C. w2 > T

A cart (weight w1) is attached by a lightweight cable to a bucket (weight w2) as shown. The ramp is frictionless. The pulley is frictionless and does not rotate. When released, the cart accelerates up the ramp and the bucket accelerates downward. How does the cable tension T compare to w2? A. T = w2 B. T > w2 C. w2 > T D. Two of the above are possible, depending on the acceleration. E. All three of the above are possible, depending on the acceleration.

B. zero

A conveyor belt is moving to the left. It has been running for a while and is moving at a constant speed. A package moves to the left on the conveyor belt without slipping. The force of friction on the package is A. to the right B. zero C. to the left

C. C

A fellow student spins a ball on a string in front of them. The ball undergoes uniform circular motion in the vertical plane. The string breaks at the moment shown below. Which picture most correctly depicts the subsequent motion of the ball? A. A B. B C. C D. D

B. B

A fellow student spins a ball on a string over the head (like a helicopter). The ball undergoes uniform circular motion in the horizontal plane. The string breaks at the moment shown below. Which picture most correctly depicts the subsequent motion of the ball? A. A B. B C. C D. D

A. mg > N

A mass m accelerates downward along a frictionless inclined plane. The magnitudes of the forces on the free-body diagram have not been drawn carefully, but the directions of the forces are correct. Which statement below is true? A. mg > N B. N > mg C. N = mg

E. E

A mass m is placed on a rough incline at an angle ϴ from horizontal. A force F is applied up the incline large enough to push the block up the incline. What is the direction of the frictional force? A. A B. B C. C D. D E. E F. More than one of the above.

B. B

A mass m is placed on a rough incline at an angle ϴ from horizontal. A force F is applied up the incline to prevent the mass from sliding down the incline. The force is just enough to prevent the mass from sliding down the incline. What is the direction of the frictional force? A. A B. B C. C D. D E. E F. More than one of the above.

B. slows down all the time.

A train car moves along a long straight track. The graph shows the position as a function of time for this train. The graph shows that the train: A. speeds up all the time. B. slows down all the time. C. speeds up part of the time and slows down part of the time. D. moves at a constant velocity.

D. act on two different objects.

An action/reaction pair of forces A. point in the same direction. B. act on the same object. C. are always long-range forces. D. act on two different objects.

B. At C only

An object moves at constant speed along the path pictured at right. At which of A, C or E (if any) is its acceleration zero? A. At A only B. At C only C. At E only D. Everywhere (constant speed) E. None of the above

E. Graph 5

An object, confined to move in only 1 direction, starts from rest and undergoes a positive acceleration for 10 seconds. After that time it continues with a constant velocity. Which graph describes this situation? A. Graph 1 B. Graph 2 C. Graph 3 D. Graph 4 E. Graph 5

C. 3 ft

At t = 0, a ball, initially at rest, starts to roll down a ramp with a constant acceleration. Suppose it moves 1 foot between t = 0 s and t = 1 s. How far does it move between t = 1 s and t = 2 s? A. 1 ft B. 2 ft C. 3 ft D. 4 ft E. 6 ft

A = C = F < E = B < D

Below are 3 scenarios with blocks being pulled to the left across a frictionless surface. The accelerations in all three scenarios are the same and the blocks are identical. < = less than = = equal to Rank the tensions in the ropes. A B C D E F

A. The ball is held at rest in your hand

Consider the following free-body diagram for a ball: Which of the following situations could the diagram apply to? Choose all that apply. A. The ball is held at rest in your hand. B. The ball is falling downward after being dropped. C. The ball is moving upward just after being thrown upward.

B. 9.8 m/s2.

If you drop an object in the absence of air resistance, it accelerates downward at 9.8 m/s2 after you let it go. If instead you throw it downward, its acceleration after release is A. less than 9.8 m/s2. B. 9.8 m/s2. C. more than 9.8 m/s2.

A. is always zero.

In the monkey shoot problem from the worksheet, the horizontal component of a projectile's acceleration A. is always zero. B. remains a non-zero constant. C. continuously increases. D. continuously decreases. E. first decreases and then increases.

E. It remains constant.

In the monkey shoot problem from the worksheet, which of the following best describes the horizontal component of the ball's velocity? Assume air resistance is negligible. A. It is zero. B. It continually increases. C. It continually decreases. D. It initially decreases and then increases. E. It remains constant.

E. They both hit at the same time.

In the simultaneous shot example, from your PLA and in class, two balls are launched from the same height and at the same time. One ball is released from rest. The other ball is shot out horizontally (with initial velocity only in the x direction). If there is no air resistance, which ball hits the ground first? A. Answer depends on the speed with which the second ball is shot. B. Answer depends on the speed with which the second ball is shot and the masses of the balls. C. The dropped ball hits first. D. The ball shot horizontally hits first. E. They both hit at the same time.

A. greater

On a carousel (merry-go-round), if you sit on one of the horses near the outer edge, you will experience a greater or smaller centripetal acceleration than if you would sit on one of the horses near the center? A. greater B. smaller C. they are the same D. it depends on the speed of the carousel

A < C < E < F < B < D

Shown above are six velocity-time graphs for toy robots that are traveling along a straight course. All robots are initially facing the same way. All graphs have the same time and velocity scale. Note that the time axis has an arrow at the end of it! Rank these situations on the basis of the displacement (where the largest negative displacement is the "least" and the largest positive displacement is the "greatest"). < = least A B C D E F

B. Four times

Suppose you double the speed at which you round a bend in the curve, by what factor must the centripetal force change to prevent you from skidding? A. Double B. Four times C. Half D. One-quarter

D. larger in magnitude & in the same direction.

The diagram shows two blocks (on a frictionless horizontal surface) with two external forces acting, one on each block as shown. Compared to the net force on the smaller block, the net force on the larger block is _____ A. equal in magnitude & opposite in direction. B. equal in magnitude & in the same direction. C. larger in magnitude & opposite in direction. D. larger in magnitude & in the same direction. E. smaller in magnitude & opposite in direction. F. smaller in magnitude & in the same direction. G. zero, since both net forces vanish & have no direction.

C. Both trains have the same velocity at some time before tB.

The graph shows position as a function of time for two trains running on parallel tracks. Which is true: A. At time tB, both trains have the same velocity. B. Both trains speed up all the time. C. Both trains have the same velocity at some time before tB. D. At some instant, both trains have the same acceleration. E. None of the above statements is true

C. mg > T

The top block is accelerated across a frictionless table by the falling mass m. The string is massless, and the pulley is both massless and frictionless. The tension in the string is A. T > mg B. T = mg C. mg > T

540

The train moves along the straight track such that its v-t graph is as shown. Determine position, in units of [m], when t=60 s. Assume that position s=0 when t=0 s. Hint position is the area of the velocity curve b/w 0 < t < 60.

-0.4

The train moves along the straight track such that its v-t graph is as shown. Find the acceleration, in units of [m/s^2], at t=100 s. Hint the slope of the curve at t = 100 s indicates the acceleration at that instant.

D. The blue ball passes the grey ball.

This figure depicts a multi-flash photo of two balls travelling to the right. Both balls at shown at several numbered times. In the figure... A. Both balls have the same velocity. B. Both balls have the same speed at flash 2. C. The grey ball will eventually pass the blue ball. D. The blue ball passes the grey ball.

D. The two balls have the same acceleration

This figure depicts a multi-flash photo of two balls travelling to the right. Both balls at shown at several numbered times. In the figure... A. Neither ball passes the other. B. Both balls are accelerating at a non-zero steady rate. C. The upper ball passes the bottom ball. D. The two balls have the same acceleration.

A. A

Two objects (A and B) are launched at the same time. They follow the paths shown below: Which object hits the ground last? A. A B. B C. They hit at the same time D. Not enough information to know

A. increases

Two stones are dropped into a bottomless pit. The second stone is dropped two seconds after the first stone. Assume no air resistance. As both stones fall, the difference in their heights A. increases B. decreases C. remains constant

C. remains constant

Two stones are dropped into a bottomless pit. The second stone is dropped two seconds after the first stone. Assume no air resistance. As both stones fall, the difference in their velocities A. increases B. decreases C. remains constant

D. t=3

When do these two objects have the same speed? A. t=0 B. t=1 C. t=2 D. t=3 E. t=4 F. t=5 G. never

B. less than mpg

You are standing on a scale in an elevator that is travelling upward to the 4th floor. As it arrives at the 4th floor the elevator slows to a stop. As the elevetor is coming to a stop the scale shows your weight (your mass = mp) as... A. greater than mpg B. less than mpg C. equal to mpg D. zero

E. The force of friction is the same for all 4 blocks.

You have a block (shown below) that you slide across a table 4 times. Once you slide it on its back (1), then you rotate it 90 degrees and slide it again (2), then you rotate it back and flip it over and slide it again (3), and finally you slide it exactly as you did the first time but with a starting velocity twice as large as the first trial (4). These are your 4 trials (shown below as 1-4). The kinetic frictional coefficient between the block and the table never changes. In which case is the force of friction between the block and the table the greatest? A. Block 1 B. Block 2 C. Block 3 D. Block 4 E. The force of friction is the same for all 4 blocks.

C. first in opposite directions and then in the same direction.

You throw a ball vertically upward. After the ball has left your hand the ball's velocity and acceleration vectors are A. always in opposite directions. B. first in the same direction and then in opposite directions. C. first in opposite directions and then in the same direction. D. always in the same direction.

B. directed downward.

You toss a ball straight up in the air. It rises up toward the sky, reaches its highest point, and then falls back into your hands. During this time the acceleration of the ball is always A. in the direction of motion. B. directed downward. C. directed upward. D. opposite its velocity. E. none of the above