Final Exam Practice Test (MC Questions)

Suppose that a car traveling to the west (-x direction) begins to slow down as it approaches a traffic light. Which statement concerning its acceleration must be correct?

Its acceleration is positive.

Inside of a train a ball of weight W is hanging by a light wire at rest from the ceiling. The wire makes an angle θ with the ceiling, as shown in the figure. Which one of the following conditions must be true about the tension T in the wire?

T sin θ = W

A pilot drops a package from a plane flying horizontally at a constant speed. Neglecting air resistance, when the package hits the ground the horizontal location of the plane will

be directly over the package.

In the figure, what does the spring scale read? The pulleys are ideal and the strings and scale are also massless.

exactly 1N

When a ball is thrown straight up with no air resistance, the acceleration at its highest point

is downward

Which of the following quantities are units of momentum? (There could be more than one correct choice.)

kg * m/s N * s

If the velocity versus time graph of an object is a horizontal line, the object is

moving with constant non-zero speed.

You are in a forward-moving train traveling on a horizontal track and notice that a piece of luggage starts to slide directly toward the back of the train. From this observation, you can conclude that this train is

speeding up.

A force produces power P by doing work W in a time T. What power will be produced by a force that does six times as much work in half as much time?

12

For general projectile motion with no air resistance, the horizontal component of a projectile's acceleration

The horizontal component of a projectile's acceleration is zero.

A ball is thrown horizontally from the top of a tower at the same instant that a stone is dropped vertically. Which object is traveling faster when it hits the level ground below if neither of them experiences any air resistance?

the ball

When a car goes around a circular curve on a horizontal road at constant speed, what force causes it to follow the circular path?

the friction force from the road

If you were to move into outer space, far from any stars or planets,

your weight would change, but your mass would not change.

Four vectors, , , , and , are shown in the figure. The sum of these four vectors is a vector having magnitude and direction

4.0 cm, along -y-axis.

Person X pushes twice as hard against a stationary brick wall as person Y. Which one of the following statements is correct?

Both do zero work.

Consider two less-than-desirable options. In the first you are driving 30 mph and crash head-on into an identical car also going 30 mph. In the second option you are driving 30 mph and crash head-on into a stationary brick wall. In neither case does your car bounce back from the thing it hits, and the collision time is the same in both cases. Which of these two situations would result in the greater impact force on your car?

The force would be the same in both cases.

Identical forces act for the same length of time on two different objects. The magnitude of the change in momentum of the lighter object is

exactly equal to the magnitude of the change in momentum of the larger mass.

In an inelastic collision involving an isolated system, the final total momentum is

exactly the same as the initial momentum.

A child standing on a bridge throws a rock straight down. The rock leaves the child's hand at time t = 0 s. If we take upward as the positive direction, which of the graphs shown below best represents the acceleration of the stone as a function of time?

*straight line in the negative part of the graph

The graph in the figure shows the position of a particle as it travels along the x-axis. What is the magnitude of the average speed of the particle between t = 1.0 s and t = 4.0 s?

0.67 m/s

A ball is thrown with an initial velocity of 20 m/s at an angle of 60° above the horizontal. If we can neglect air resistance, what is the horizontal component of its instantaneous velocity at the exact top of its trajectory?

10 m/s 20*cos(60)

A cart starts from rest and accelerates uniformly at 4.0 m/s2 for 5.0 s. It next maintains the velocity it has reached for 10 s. Then it slows down at a steady rate of 2.0 m/s2 for 4.0 s. What is the final speed of the car?

12 m/s

A racquetball strikes a wall with a speed of 30 m/s and rebounds in the opposite direction with a speed of 26 m/s. The collision takes 20 ms. What is the average acceleration of the ball during the collision with the wall?

2800 m/s2

Two vectors, of magnitudes 20 mm and 50 mm, are added together. Which one of the following is a possible value for the magnitude of the resultant?

40 mm

Which requires more work, increasing a car's speed from 0 mph to 30 mph or from 50 mph to 60 mph?

50 mph to 60 mph

A truck is using a hook to tow a car whose mass is one quarter that of the truck. If the force exerted by the truck on the car is 6000 N, then the force exerted by the car on the truck is

6000 N.

The figure shows a graph of the velocity of an object as a function of time. What is the displacement of the object from 0 s to 6.0 s?

80m

A girl attaches a rock to a string, which she then swings counter-clockwise in a horizontal circle. The string breaks at point P in the figure, which shows a bird's-eye view (as seen from above). Which path (A-E) will the rock follow?

B

REPEAT (Q28): Person X pushes twice as hard against a stationary brick wall as person Y. Which one of the following statements is correct?

Both do zero work.

A heavy rock and a light rock are dropped from the same height and experience no significant air resistance as they fall. Which of the following statements about these rocks are correct? (There could be more than one correct choice.)

Both rocks have the same speed when they reach the ground. When they reach the ground, the heavier rock has more kinetic energy than the lighter rock.

You are standing on a skateboard, initially at rest. A friend throws a very heavy ball towards you. You have two choices about what to do with the ball: either catch the ball or deflect it back toward your friend with the same speed as it was originally thrown. Which choice should you make in order to maximize your speed on the skateboard?

Deflect the ball back.

A block of mass m sits at rest on a rough inclined ramp that makes an angle θ with the horizontal. What must be true about normal force F on the block due to the ramp?

F = mg cos θ

You slam on the brakes of your car in a panic, and skid a certain distance on a straight level road. If you had been traveling twice as fast, what distance would the car have skidded, under the same conditions?

It would have skidded 4 times farther

Two blocks, A and B, are being pulled to the right along a horizontal surface by a horizontal 100-N pull, as shown in the figure. Both of them are moving together at a constant velocity of 2.0 m/s to the right, and both weigh the same.

No forces are acting upon block A.

Suppose that an object is moving with a constant velocity. Which statement concerning its acceleration must be correct?

The acceleration is equal to zero.

Suppose that a car traveling to the west begins to slow down as it approaches a traffic light. Which of the following statements about its acceleration is correct?

The acceleration is toward the east.

Under what condition is average velocity equal to the average of the object's initial and final velocity?

The acceleration must be constant.

Suppose that an object travels from one point in space to another. Make a comparison between the magnitude of the displacement and the distance traveled by this object.

The displacement is either less than or equal to the distance traveled.

Which of the following statements are true about an object in two-dimensional projectile motion with no air resistance? (There could be more than one correct choice.)

The horizontal acceleration is always zero and the vertical acceleration is always a non-zero constant downward.

A very elastic rubber ball is dropped from a certain height and hits the floor with a downward speed v. Since it is so elastic, the ball bounces back with the same speed v going upward. Which of the following statements about the bounce are correct?

The magnitude of the ball's momentum was the same just before and just after the bounce.

Here is a graph of an object's motion. Which sentence is a correct interpretation?

The object doesn't move at first. Then it moves backwards and then finally stops.

If the force on an object is in the negative direction, the work it does on the object must be

The work could be either positive or negative, depending on the direction the object moves.

A person stands on the edge of a cliff. She throws three identical rocks with the same speed. Rock X is thrown vertically upward, rock Y is thrown horizontally, and rock Z is thrown vertically downward. If the ground at the base of the cliff is level, which rock hits the ground with the greatest speed if there is no air resistance?

They all hit the ground with the same speed.

Two objects are thrown from the top of a tall building. One is thrown up, and the other is thrown down, both with the same initial speed. What are their speeds when they hit the street? Neglect air resistance.

They are traveling at the same speed.

In a collision between two unequal masses, which mass receives a greater magnitude impulse?

They receive equal impulses.

An auto manufacturer advertises that their car can go "from zero to sixty in eight seconds." This is a description of what characteristic of the car's motion?

average acceleration

Which of the following graphs represent an object having zero acceleration? (Note that vertical axes are not all the same.)

both a and b

When a rifle is fired, it recoils as the bullet is set in motion. The rifle and bullet ideally acquire equal

but opposite amounts of momentum.

A stone is held at a height h above the ground. A second stone with four times the mass of the first one is held at the same height. The gravitational potential energy of the second stone compared to that of the first stone is

four times as much.

A 10-kg rock and a 20-kg rock are thrown upward with the same initial speed v0 and experience no significant air resistance. If the 10-kg rock reaches a maximum height h, what maximum height will the 20-kg ball reach?

h

You drive 6.0 km at 50 km/h and then another 6.0 km at 90 km/h. Your average speed over the 12 km drive will be

less than 70 km/h given that d1=6 km v1=50km/h d2=6 km v2=90 km/h overall distance which is drived =d1+d2= 12km time taken to drive d1 distance =6/50 h time taken to drive d2 distance=6/90 h total time taken to drive 12 km distance=6/50+6/90=0.18 h average speed =total distance/total time average speed= 12/0.18=66.66 km/h

A block is at rest on a rough incline as shown. The frictional force acting on the block, along the incline, is

less than the weight of the block.

A crate is sliding down an inclined ramp at a constant speed of 0.55 m/s. The vector sum of all the forces acting on this crate must point

none of the above choices is correct

On a horizontal frictionless air table, a puck runs into an ideal horizontal spring that is fastened to the table. The puck compresses the spring by 15 cm before coming to rest. During the compression process, which quantities are conserved?

only the mechanical energy (kinetic plus potential) of the puck

In the figure, determine the character of the collision. The masses of the blocks, and the velocities before and after, are shown. The collision is

perfectly elastic

Two equal-magnitude forces are applied to a door at the doorknob. The first force is applied perpendicular to the door, and the second force is applied at 30° to the plane of the door. Which force exerts the greater torque about the door hinge?

the first force (applied perpendicular to the door)

Two forces produce equal torques on a door about the door hinge. The first force is applied at the midpoint of the door; the second force is applied at the doorknob. Both forces are applied perpendicular to the door. Which force has a greater magnitude?

the first force (at the midpoint)

Two objects of different mass have equal, non-zero kinetic energies. Which object has the greater magnitude momentum?

the heavier object

Two objects of different masses have momentum of equal, non-zero magnitude. Which object has more kinetic energy?

the lighter object

When a car goes around a banked circular curve at the proper speed speed for the banking angle, what force cause it to follow the circular path?

the normal force from the road

A brick initially has its largest-area face in contact with a rough surface, as shown on the left in the figure. A force F is required to pull the brick along the surface at constant speed. The brick is now flipped so that a face of smaller area is in contact, as on the right in the figure. The material of the brick is uniform on all faces. What force is now required to pull the brick along at constant speed as before?

the same force

During World War I, Germany used a "Big Bertha" cannon to hurl shells into Paris 30 miles away. This gun also had a very long barrel. What was the reason for using a long barrel in these guns?

to allow the force of the expanding gases from the gunpowder to act for a longer time

A ball is thrown straight up, reaches a maximum height, then falls to its initial height. Which of the following statements about the direction of the velocity and acceleration of the ball as it is going up is correct?

Its velocity points upward and its acceleration points downward.

A truck has four times the mass of a car and is moving with twice the speed of the car. If Kt and Kc refer to the kinetic energies of truck and car respectively, it is correct to say that

Kt = 16Kc.

The area under a curve in a velocity versus time graph gives

displacement

A block of mass m sits at rest on a rough inclined ramp that makes an angle θ with the horizontal. What must be true about force of static friction f on the block?

f = mg sin θ

A person who normally weighs 700 N is riding in an elevator that is moving upward but slowing down at a steady rate. If this person is standing on a bathroom scale inside the elevator, what would the scale read?

less than 700N

Swimmers at a water park have a choice of two frictionless water slides, as shown in the figure. Although both slides drop over the same height h, slide 1 is straight while slide 2 is curved, dropping quickly at first and then leveling out. How does the speed v1 of a swimmer reaching the bottom of slide 1 compare with v2, the speed of a swimmer reaching the end of slide 2?

v1 = v2

The slope of a position versus time graph gives

velocity.

If you are driving 44 mi/h along a straight road and you look to the side for 4.0 s, how far do you travel during this inattentive period?

80 m