Physics Semester 1 Multiple Choice Chapters 2-4

A 200-N sled of slides down a friction less hillside that rises at 37* above the horizontal. What is the magnitude of the force that the hill exerts on the sled parallel to the surface of the hill? A- 200 N B- 120 N C- 160 N D- 0 N E- 150 N

0 N

A 200-N sled of slides down a friction less hillside that rises at 37* above the horizontal. What is the magnitude of the force that the surface of the hill exerts on the sled? A- 120 N B- 160 N C- 200 N D- 0 N E- 150 N

160 N

Which of the following quantities has units of displacement? A- -120 m/s B- 186,000 mi C- 40 km southwest D- 32 ft/s^2 vertically downward E- 9.8 m/s^2

40 km southwest (displacement is a vector)

The figure shows a graph of the position x of two cars, C and D, as a function of time t. According to this graph, which statements about these cars must be true? (There could be more than one correct choice.) A- The magnitude of the acceleration of car C is greater than the magnitude of the acceleration of car D. B- The magnitude of the acceleration of car C is less than the magnitude of the acceleration of car D. C- At time t = 10 s, both cars have the same velocity. D- Both cars have the same acceleration. E- The cars meet at time t = 10 s.

Both cars have the same acceleration. The cars meet at time t = 10 s.

Mary and Debra stand on a snow-covered roof. They both throw snowballs with the same initial speed, but in different directions. Mary throws her snowball downward, at 30° below the horizontal; Debra throws her snowball upward, at 30° above the horizontal. Which of the following statements are true about just as the snowballs reach the ground below? (There are two correct choices.) A- Both snowballs will hit the ground with the same speed. B- Mary's snowball reaches the ground before Debra's snowball. C- Debra's snowball will have a higher speed than Mary's snowball. D- Both snowballs hit the ground at the same time. E- Mary's snowball will have a higher speed than Debra's snowball.

Both snowballs will hit the ground with the same speed. Mary's snowball reaches the ground before Debra's snowball.

A 20-ton truck collides with a 1500-lb car. Which of the following statements must be true? A- During the collision, the force on the truck is greater than the force on the car. B- The car did not slow down during the collision, but the truck did. C- During the collision, the force on the truck is equal to the force on the car. D- During the collision, the force on the truck is smaller than the force on the car.

During the collision, the force on the truck is equal to the force on the car.

A satellite is in orbit around the earth. Which one feels the greater force? A- The satellite because the earth is so much more massive. B- The earth because the satellite has so little mass. C- It depends on the distance of the satellite from Earth. D- Earth and the satellite feel exactly the same force.

Earth and the satellite feel exactly the same force.

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? A- F = mg sin θ B- F > mg cos θ C- F > mg D- F > mg sin θ E- F = mg cos θ

F = mg cos θ

If the acceleration of an object is zero, then that object cannot be moving. A- True. B- False.

False.

If the velocity of an object is zero at some point, then its acceleration must also be zero at that point. A- True. B- False.

False.

If three vectors add to zero, they must all have equal magnitudes. A- True. B- False.

False.

In a collision between a huge SUV and a small hybrid car, the SUV exerts a larger force on the hybrid than the hybrid exerts on the SUV. A- True. B- False. C- It depends on whether the collision is a head-on collision or a rear-end collision.

False.

In order to get an object moving, you must push harder on it than it pushes back on you. A- True. B- False.

False.

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? A- Its acceleration is decreasing in magnitude as the car slows down. B- Its acceleration is positive. C- Its acceleration is zero. D- Its acceleration is negative.

Its acceleration is positive.

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? A- Its velocity points upward and its acceleration points downward. B- Both its velocity and its acceleration points downward. C- Its velocity points downward and its acceleration points upward. D- Both its velocity and its acceleration point upward.

Its velocity points upward and its acceleration points downward.

The acceleration due to gravity is lower on the Moon than on Earth. Which one of the following statements is true about the mass and weight of an astronaut on the Moon's surface, compared to the Earth? A- Both mass and weight are the same. B- Both mass and weight are less. C- Mass is less, weight is the same. D- Mass is same, weight is less.

Mass is same, weight is less.

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. Which of the figures below shows a correct free-body diagram of the horizontal forces acting on the upper block, A? A- Two 100 N forces pulling to the right. B- One 100 N force pulling to the right. C- No horizontal forces act on A. D- One 100 N force pulling to the right, one 100 N force pulling to the left. E- One 50 N force pulling to the right.

No horizontal forces act on A.

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 A- up the ramp. B- perpendicular to the ramp. C- vertically downward. D- down the ramp. E- None of the above choices are correct.

None of the above choices are correct.

In the figure, a 10-lb weight is suspended from two spring scales, each of which has negligible weight. Which one of the following statements about the readings in the scales is true? A- Each scale will read 5 lb. B- The top scale will read zero, the lower scale will read 10 lb. C- Each scale will read 5 lb. D- None of these is true.

None of these is true.

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. Which of the figures below shows a correct free-body diagram of the horizontal forces acting on the lower block, B? A- One 100 N force pulling to the right. B- One 100 N force pulling to the right, one 100 N force pulling to the left. C- Two 50 N forces pulling to the left, one 100 N force pulling to the right. D- Two 100 N forces pulling to the left, one 100 N force pulling to the right. E- None of these diagrams is correct.

One 100 N force pulling to the right, one 100 N force pulling to the left.

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? A- Path A. B- Path B. C- Path C. D- Path D. E- Path E.

Path B.

Two boxes are connected to each other by a string as shown in the figure. The 10-N box slides without friction on the horizontal table surface. The pulley is ideal and the string has negligible mass. What is true about the tension T in the string? A- T = 10 N B- T = 20 N C- T = 30 N D- T < 30 N E- T > 30 N

T < 30 N

Three boxes are pulled along a horizontal frictionless floor by a constant horizontal pull P. The boxes are connected by very light horizontal strings having tensions T1 and T2 as shown in the figure. Which of the following statements about the tensions is correct? (There could be more than one correct choice.) A- T1 > T2 B- T1 = P C- T1 + T2 = P D- T2 > T1 E- T2 = P

T1 > T2

If the velocity of an object is zero at one instant, what is true about the acceleration of that object? (There could be more than one correct choice) A- The acceleration must be zero. B- The acceleration could be positive. C- The acceleration could be zero. D- The acceleration could be negative.

The acceleration could be positive. The acceleration could be zero. The acceleration could be negative.

A rock from a volcanic eruption is launched straight up into the air with no appreciable air resistance. Which one of the following statements about this rock while it is in the air is correct? A- On the way up, its acceleration is downward and its velocity is upward, and at the highest point both its velocity and acceleration are zero. B- The acceleration is downward at all points in the motion except that is zero at the highest point. C- On the way down, both its velocity and acceleration are downward, and at the highest point both its velocity and acceleration are zero. D- The acceleration is downward at all points in the motion. E- Throughout the motion, the acceleration is downward, and the velocity is always in the same direction as the acceleration.

The acceleration is downward at all points in the motion.

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? A- The acceleration is zero. B- Since the car is slowing down, its acceleration must be negative. C- The acceleration is toward the west. D- The acceleration is toward the east.

The acceleration is toward the east.

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? A- It is impossible to tell because we do not know their masses. B- The stone. C- The ball. D- Both are traveling at the same speed.

The ball.

When a 45-kg person steps on a scale in an elevator, the scale reads a steady 480 N. Which of the following statements must be true? (There are two correct choices) A- The elevator is accelerating downward at a constant rate. B- The elevator is accelerating upward at a constant rate. C- The elevator is moving downward at a constant rate. D- The elevator is moving upward at a constant rate. E- From the given information, we cannot tell if the elevator is moving up or down.

The elevator is accelerating upward at a constant rate. From the given information, we cannot tell if the elevator is moving up or down.

A fireman is sliding down a fire pole. As he speeds up, he tightens his grip on the pole, thus increasing the vertical frictional force that the pole exerts on the fireman. When the force on his hands equals his weight, what happens to the fireman? A- The fireman descends with a smaller but non-zero acceleration. B- The fireman descends with slower and slower speed. C- The fireman comes to a stop. D- The fireman continues to descend, but with constant speed. E- The acceleration of the fireman is now upward.

The fireman continues to descend, but with constant speed.

Which of the following statements are true about an object in two-dimensional projectile motion with no air resistance? A- The acceleration of the object is zero at its highest point. B- The speed of the object is constant but its velocity is not constant. C- The speed of the object is zero at its highest point. D- The horizontal acceleration is always zero and the vertical acceleration is always a non-zero constant downward. E- The acceleration of the object is +g when the object is rising and -g when it is falling.

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

From the edge of a roof top you toss a green ball upwards with initial speed v0 and a blue ball downwards with the same initial speed. Air resistance is negligible. When they reach the ground below A- The green ball will be moving faster than the blue ball. B- The blue ball will be moving faster than the green ball. C- The two balls will have the same speed.

The two balls will have the same speed.

You are standing in a moving bus facing forward when you suddenly slide forward as the bus comes to an immediate stop. What force caused you to slide forward? A- Gravity. B- The force due to friction between you and the floor of the bus. C- The normal force due to your contact with the floor of the bus. D- There is not a force causing you to slide forward.

There is not a force causing you to slide forward.

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. A- The one thrown up is traveling faster. B- They are traveling at the same speed. C- The one thrown down is traveling faster. D- It is impossible to tell because the height of the ball is not given.

They are traveling at the same speed.

In an air-free chamber, a pebble is thrown horizontally, and at the same instant a second pebble is dropped from the same height. Compare the times of fall of the two pebbles. A- The thrown pebble hits first. B- They hit at the same time. C- The dropped pebble hits first. D- We cannot tell without knowing which pebble is heavier.

They hit at the same time.

A boulder rolls off of a very high cliff and experiences no significant air resistance. While it is falling, its trajectory is never truly vertical. A- True. B- False.

True.

Consider a car that travels between points A and B. The car's average speed can be greater than the magnitude of its average velocity, but the magnitude of its average velocity can never be greater than its average speed. A- True. B- False.

True.

A push of magnitude P acts on a box of weight W as shown in the figure. The push is directed at an angle θ below the horizontal, and the box remains a rest. The box rests on a horizontal surface that has some friction with the box. The normal force on the box due to the floor is equal to A- W + P B- W - P sin θ C- W D- W + P cos θ E- W + P sin θ

W + P sin θ

A 10-kg rock and a 20-kg rock are dropped at the same time and experience no significant air resistance. If the 10-kg rock falls with acceleration a, what is the acceleration of the 20-kg rock? A- a B- 4a C- a/4 D- 2a

a

An object is moving with constant non-zero velocity in the +x direction. The velocity versus time graph of this object is A- a horizontal straight line. B- a vertical straight line. C- a straight line making an angle with the time axis. D- a parabolic curve.

a horizontal straight line.

An object is moving with constant non-zero velocity in the +x direction. The position versus time graph of this object is A- a horizontal straight line. B- a vertical straight line. C- a straight line making an angle with the time axis. D- a parabolic curve.

a straight line making an angle with the time axis.

A 75 N box rests on a perfectly smooth horizontal surface. The minimum force needed to start the box moving is A- 7.5 N. B- 750 N. C- 75 N. D- any horizontal force greater than zero.

any horizontal force greater than zero.

If the position versus time graph of an object is a horizontal line, the object is A- moving with constant non-zero speed. B- moving with constant non-zero acceleration. C- at rest. D- moving with increasing speed.

at rest.

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 A- be directly over the package. B- be in front of the package. C- depend on the speed of the plane when the package was released. D- be behind the package.

be directly over the package.

A racing car accelerates uniformly along a straight track. This track has markers at equal distances along it from the start, as shown in the figure. The car reaches a speed of 140 km/h as it passes marker 2. Where on the track was the car when it was traveling at half this speed, that is at 70 km/h? A- at marker 1 B- before marker 1 C- between marker 1 and marker 2

before marker 1

Consider two vectors A and B shown in the figure. The difference A - B is best illustrated by

c

Two objects of unequal masses, M and m (M > m), are connected by a very light cord passing over an ideal pulley of negligible mass. When released, the system accelerates, and friction is negligible. Which one of the following free-body diagrams most realistically represents the forces acting on the two objects in the moving system?

c

Two displacement vectors have magnitudes of 5.0 m and 7.0 m, respectively. If these two vectors are added together, the magnitude of the sum A- is equal to 8.6m. B- is equal to 2.0m. C- could be as small as 2.0m or as large as 12m. D- is equal to 12.0m.

could be as small as 2.0m or as large as 12m.

The motion of a particle is described in the velocity vs. time graph shown in the figure. Over the nine-second interval shown, we can say that the speed of the particle A- remains constant. B- only increases. C- increases and then decreases. D- decreases and then increases. E- only decreases.

decreases and then increases.

An object of weight W is in freefall close to the surface of Earth. The magnitude of the force that the object exerts on Earth is A- greater than W. B- cannot be determined without knowing the relative masses of the object and the earth. C- equal to W. D- less than W. E- zero.

equal to W.

A bucket is being lowered by a very light rope with a constant downward velocity. The tension in the rope must be A- greater than the weight of the bucket. B- equal to the weight of the bucket. C- less than the weight of the bucket.

equal to the weight of the bucket.

In the figure, what does the spring scale read? The pulleys are ideal and the strings and scale are also massless. A- more than 19.6 N. B- 0.50 N. C- exactly 1.0 N. D- exactly 2.0 N. E- 0.00 N.

exactly 1.0 N.

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 the force of static friction f on the block? A- f > mg cos θ B- f = mg cos θ C- f > mg sin θ D- f > mg E- f = mg sin θ

f = mg sin θ

Which of the following graphs represent an object at rest? (There could be more than one correct choice.)

graph a

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?

graph c

An elevator suspended by a vertical cable is moving downward but slowing down. The tension in the cable must be A- less than the weight of the elevator. B- greater than the weight of the elevator. C- equal to the weight of the elevator.

greater than the weight of the elevator.

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 rock reach? A- h/4 B- 2h C- 4h D- h E- h/2

h

You are trying to cross a river that flows toward the south with a strong current. You start out in your motorboat on the east bank desiring to reach the west bank directly west from your starting point. You should head your motorboat A- directly toward the north. B- in a general southwesterly direction. C- directly toward the west. D- in a general northwesterly direction.

in a general northwesterly direction.

For general projectile motion with no air resistance, the horizontal component of a projectile's acceleration A- remains a non-zero constant. B- is always zero. C- continuously decreases. D- first decreases and then increases. E- continuously increases.

is always zero.

An object moving in the +x direction experiences an acceleration of +0.2 m/s^2. This means the object A- travels 2.0 m in every second. B- is increasing its velocity by 2.0 m/s every second. C- is traveling at 2.0 m/s. D- is decreasing its velocity by 2.0 m/s every second.

is increasing its velocity by 2.0 m/s every second.

The figure shows two boxes, with m1 > m2, that are on a level frictionless surface. We can apply a horizontal force F either toward the right on m1 or toward the left on m2. The magnitude of the force that the boxes exert on each other is A- larger if F is applied toward the right. B- zero newtons in either case. C- larger if F is applied toward the left. D- the same in either case.

larger if F is applied toward the left.

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? A- 700 N. B- more than 700 N. C- less than 700 N. D- It could be more or less than 700 N, depending on whether the magnitude of the acceleration is greater than or less than 9.8 m/s^2.

less than 700 N.

If the velocity versus time graph of an object is a straight line making an angle of +30* (counter clockwise) with the time axis, the object is A- moving with constant non-zero speed. B- moving with constant non-zero acceleration. C- at rest. D- moving with increasing acceleration.

moving with constant non-zero acceleration.

A player kicks a soccer ball in a high arc toward the opponent's goal. At the highest point in its trajectory A- the ball's velocity points downward. B- the ball's acceleration points upward. C- both the velocity and the acceleration of the soccer ball are zero. D- the ball's acceleration is zero but its velocity is not zero. E- neither the ball's velocity nor its acceleration are zero.

neither the ball's velocity nor its acceleration are zero.

For general projectile motion with no air resistance, the horizontal component of a projectile's velocity A- first decreases and then increases. B- continuously increases. C- remains zero. D- continuously decreases. E- remains a non-zero constant.

remains a non-zero constant.

For general projectile motion with no air resistance, the vertical component of a projectile's acceleration A- continuously increases. B- is always zero. C- first decreases and then increases. D- remains a non-zero constant. E- continuously decreases.

remains a non-zero constant.

The slope of a position versus time graph gives A- acceleration. B- the distance traveled. C- velocity. D- displacement.

velocity.

When is the average velocity of an object equal to the instantaneous velocity? A- when the velocity is constant B- only when the velocity is decreasing at a constant rate C- never D- only when the velocity is increasing at a constant rate E- always

when the velocity is constant