PHYS201 Multiple Choice

An object experiences no acceleration. Which of the following CANNOT be true for the object? 1. A single force acts on the object. 2. No forces act on the object. 3. Forces act on the object, but the forces cancel.

1) a single force acts on the object

You tie a rope to a tree and you pull on the rope with a force of 100 N. What is the tension in the rope?

100 N

A rigid object rotates in a counterclockwise sense around a fixed axis. Each of the following pairs of quantities represents an initial angular position and a final angular position of the rigid object. Suppose the change in angular position for each of these pairs of values occurs in 1 s. Which choice represents the lowest average angular speed? 1. 3 rad, 6 rad 2. -1 rad, 1 rad 3. 1 rad, 5 rad

2) -1 rad, 1 rad

A rigid object rotates in a counterclockwise sense around a fixed axis. If the object starts from rest at the initial angular position, moves counterclockwise with constant angular acceleration, and arrives at the final angular position with the same angular speed in all three cases, for which choice is the angular acceleration the highest? 1. 3 rad, 6 rad 2. -1 rad, 1 rad 3. 1 rad, 5 rad

2) -1 rad, 1 rad

You press your physics textbook flat against a vertical wall with your hand. What is the direction of the friction force exerted by the wall on the book? 1. downward 2. upward 3. out from the wall 4. into the wall

2) upward

Which of the following statements is correct? 1. It is possible for an object to have motion in the absence of forces on the object. 2. It is possible to have forces on an object in the absence of motion of the object. 3. Neither 1 nor 2 is correct. 4. Both 1 and 2 are correct

4) both 1 and 2 are correct

From rest, we step on the gas of our Ferrari, providing a force F for 4 secs, speeding it up to a final speed v. If the applied force were only ½ F, how long would it have to be applied to reach the same final speed?

8 seconds

A mass on a spring in SHM has amplitude A and period T. What is the net displacement of the mass after a time interval T? a) 0 b) A/2 c) A d) 2A e) 4A

a) 0

Newton's most celebrated synthesis is of A. earthly and heavenly laws. B. weight on Earth and weightlessness in outer space. C. masses and distances. D. the paths of tossed rocks and the paths of satellites.

a) Earthly and heavenly laws

In which of the cases shown below is the torque provided by the applied force about the rotation axis biggest? For all cases the magnitude of the applied force is the same. a) F1 b) F3 c) F4 d) all of them e) none of them

a) F1 90 degrees

You see a leaf falling to the ground with constant speed. When you first notice it, the leaf has initial total energy PEi + KEi. You watch the leaf until just before it hits the ground, at which point it has final total energy PEf + KEf. How do these total energies compare? a) PEi + KEi > PEf + KEf b) PEi + KEi = PEf + KEf c) PEi + KEi < PEf + KEf d) impossible to tell from the information provided

a) PEi + KEi > PEf + KEf As the leaf falls, air resistance exerts a force on it opposite to its direction of motion. This force does negative work, which prevents the leaf from accelerating. This frictional force is a nonconservative force, so the leaf loses energy as it falls, and its final total energy is less than its initial total energy.

Three blocks of mass 3m, 2m, and m are connected by strings and pulled with constant acceleration a. What is the relationship between the tension in each of the strings? a) T1 > T2 > T3 b) T1 < T2 < T3 c) T1 = T2 = T3 d) all tensions are zero e) tensions are random

a) T1 > T2 > T3

When standing in the aisle of a smoothly riding bus, you drop a coin from above your head. The falling coin will land A. at your feet. B. slightly in front of your feet. C. slightly in back of your feet. D. at a location not listed above.

a) at your feet

When a dish falls, will the change in momentum be less if it lands on a carpet than if it lands on a hard floor? A. No, both are the same. B. Yes, less if it lands on the carpet. C. No, less if it lands on a hard floor. D. No, more if it lands on a hard floor.

a) both are the same The momentum becomes zero in both cases, so both change by the same amount. Although the momentum change and impulse are the same, the force is less when the time of momentum change is extended.

Below you see two cases: a physics student pulling or pushing a sled with a force F that is applied at an angle q. In which case is the normal force greater? a) case 1 b) case 2 c) it's the same for both d) depends on the magnitude of the force F e) depends on the ice surface

a) case 1 In case 1, the force F is pushing down (in addition to mg), so the normal force needs to be larger. In case 2, the force F is pulling up, against gravity, so the normal force is lessened.

Consider the two configurations of books shown below. Which of the following is true? a) case 1 will tip b) case 2 will tip c) both will tip d) neither will tip

a) case 1 will tip

When you pay the electric company by the kilowatthour, what are you actually paying for? a) energy b) power c) current d) voltage e) none of the above

a) energy

A cruise ship is moving at constant speed through the water. The vacationers on the ship are eager to arrive at their next destination. They decide to try to speed up the cruise ship by gathering at the bow (the front) and running together toward the stern (the back) of the ship. While they are running toward the stern, the speed of the ship is: 1. higher than it was before. 2. unchanged. 3. lower than it was before. 4. impossible to determine.

a) higher than it was before

You throw a ball straight up into the air. After it leaves your hand, at what point in its flight does it have the maximum value of acceleration? a) its acceleration is constant everywhere b) at the top of its trajectory c) halfway to the top of its trajectory d) just after it leaves your hand e) just before it returns to your hand on the way down

a) its acceleration is constant everywhere The ball is in free fall once it is released. Therefore, it is entirely under the influence of gravity, and the only acceleration it experiences is g, which is constant at all points.

The force of gravity between two planets depends on their A. masses and distance apart. B. planetary atmospheres. C. rotational motions. D. All of the above.

a) masses and distances apart F = G x (m1 x m2)/d^2

A grandfather clock has a weight at the bottom of the pendulum that can be moved up or down. If the clock is running slow, what should you do to adjust the time properly? a) move the weight up b) move the weight down c) moving the weight will not matter d) call the repairman

a) move the weight up

A ball tied to a string is being whirled around in a circle. What can you say about the work done by tension? a) tension does no work at all b) tension does negative work c) tension does positive work

a) tension does no work at all No work is done because the force acts in a perpendicular direction to the displacement. Or using the definition of work (W = F (Δr)cos )

Two paths lead to the top of a big hill. One is steep and direct, while the other is twice as long but less steep. How much more potential energy would you gain if you take the longer path? a) the same b) twice as much c) four times as much d) half as much e) you gain no PE in either case

a) the same

Given that A + B = C, and that lAl^2 + lBl^2 = lCl^2, how are vectors A and B oriented with respect to each other? a) they are perpendicular to each other b) they are parallel and in the same direction c) they are parallel but in the opposite direction d) they are at 45° to each other e) they can be at any angle to each other

a) they are perpendicular

Does a car hoisted for repairs in a service station have increased potential energy relative to the floor? A. Yes. B. No. C. Sometimes. D. Not enough information.

a) yes

If the velocity of a car is non-zero (v ¹ 0), can the acceleration of the car be zero? a) yes b) no c) depends on the velocity

a) yes

You and your dog go for a walk to the park. On the way, your dog takes many side trips to chase squirrels or examine fire hydrants. When you arrive at the park, do you and your dog have the same displacement? a) yes b) no

a) yes

Can friction ever do positive work? a) yes b) no

a) yes Consider the case of a box on the back of a pickup truck. If the box moves along with the truck, then it is actually the force of friction that is making the box move.

Paul and Kathleen start from rest at the same time on frictionless water slides with different shapes. Who makes it to the bottom first? a) P b) K c) same

b) Kathleen Even though they both have the same final velocity, Kathleen is at a lower height than Paul for most of her ride. Thus, she always has a larger velocity during her ride and therefore arrives earlier!

Acceleration and velocity are actually A. much the same as each other. B. rates, but for different quantities. C. the same when direction is not a factor. D. the same for free-fall situations

b) Rates, but for different quantities

Bonnie sits on the outer rim of a merry-go-round, and Klyde sits midway between the center and the rim. The merry-go-round makes one revolution every 2 seconds. Who has the larger linear (tangential) velocity? a) Klyde b) Bonnie c) both the same d) linear velocity is zero for both of them

b) bonnie v = rw and for Bonnie, r is larger

Where is the center of mass of a baseball bat located? a) at the midpoint b) closer to the thick end c) closer to the thin end (near handle) d) it depends on how heavy the bat is

b) closer to the thick end

The difference between speed and velocity mostly involves A. amount. B. direction. C. acceleration. D. All of the above.

b) direction

When the speed of an object is doubled, its momentum A. remains unchanged in accord with the conservation of momentum. B. doubles. C. quadruples. D. decreases.

b) doubles

You drive your car too fast around a curve and the car starts to skid. What is the correct description of this situation? a) car's engine is not strong enough to keep the car from being pushed out b) friction between tires and road is not strong enough to keep car in a circle c) car is too heavy to make the turn d) a deer caused you to skid e) none of the above

b) friction between tires and road is not strong enough to keep car in a circle

A box is being pulled across a rough floor at a constant speed. What can you say about the work done by friction? a) friction does no work at all b) friction does negative work c) friction does positive work

b) friction does negative work

A cannonball shot from a cannon with a long barrel will emerge with greater speed, because the cannonball receives a greater A. average force. B. impulse. C. Both of the above. D. Neither of the above.

b) impulse The force on the cannonball will be the same for a short- or long barreled cannon. The longer barrel provides for a longer time for the force to act and therefore a greater impulse.

When the force that produces an impulse acts for twice as much time, the impulse is A. not changed. B. increased by two times. C. increased by four times. D. decreased by half.

b) increased by 2 times

The cart is being pulled along a horizontal track by an external force and accelerating. It fires a ball straight out of the cannon as it moves. After it is fired, what happens to the ball? a) it depends upon how much the track is tilted b) it falls behind the cart c) it falls in front of the cart d) it falls right back into the cart e) it remains at rest

b) it falls behind the cart because the cart is accelerating!!!

Mike performed 5 J of work in 10 secs. Joe did 3 J of work in 5 secs. Who produced the greater power? a) Mike produced more power b) Joe produced more power c) both produced the same amount of power

b) joe divide by time

A figure skater spins with her arms extended. When she pulls in her arms, she reduces her rotational inertia and spins faster so that her angular momentum is conserved. Compared to her initial rotational kinetic energy, her rotational kinetic energy after she pulls in her arms must be a) the same b) larger because she's rotating faster c) smaller because her rotational inertia is smaller

b) larger because she's rotating faster

If the average velocity is non-zero over some time interval, does this mean that the instantaneous velocity is never zero during the same interval? a) yes b) no c)it depends

b) no

Does the displacement of an object depend on the specific location of the origin of the coordinate system? a) yes b) no c) it depends on the coordinate system

b) no Because the displacement is the difference between two coordinates, the origin does not matter.

A system of particles is known to have a total momentum of zero. Does it necessarily follow that the total kinetic energy of the system is also zero? a) yes b) no

b) no Since momentum is a vector the particles could be moving so that their momenta cancel out, making Pt=0

Two forces produce the same torque. Does it follow that they have the same magnitude? a) yes b) no c) depends

b) no T = Fd, so if the forces and distances were both different, it could yield the same torque

If the position of a car is zero, does its speed have to be zero? a) yes b) no c) it depends on the position

b) no speed depends on the CHANGE in position

Two objects are known to have the same momentum. Do these two objects necessarily have the same kinetic energy? a) yes b) no

b) no velocity could be different

Is it possible for the kinetic energy of an object to be negative? a) yes b) no

b) no velocity is squared and mass cannot be negative

Two pendula have the same length, but different masses attached to the string. How do their periods compare? a) period is greater for the greater mass b) period is the same for both cases c) period is greater for the smaller mass

b) period is the same for both cases

A mass is suspended from the ceiling of an elevator by a spring. When the elevator is at rest, the period is T. What happens to the period when the elevator is accelerating upward? a) period will increase b) period will not change c) period will decrease

b) period will not change

Your little sister wants you to give her a ride on her sled. On level ground, what is the easiest way to accomplish this? a) pushing her from behind b) pulling her from the front c) both are equivalent d) it is impossible to move the sled e) tell her to get out and walk

b) pulling her from the front smaller normal force than pushing

If the masses of two planets are each somehow doubled, the force of gravity between them A. doubles. B. quadruples. C. reduces by half. D. reduces by one quarter.

b) quadruples

You drop a package from a plane flying at constant speed in a straight line. Without air resistance, the package will: a) quickly lag behind the plane while falling b) remain vertically under the plane while falling c) move ahead of the plane while falling d) not fall at all

b) remain vertically under the plane while falling because the plane's velocity is constant!!!

Does the speedometer in a car measure velocity or speed? a) velocity b) speed c) both d) neither

b) speed no direction

You are holding a spinning bicycle wheel while standing on a stationary turntable. If you suddenly flip the wheel over so that it is spinning in the opposite direction, the turntable will: a) remain stationary b) start to spin in the same direction as before flipping c) to spin in the same direction as after flipping

b) start to spin in the same direction as before flipping

Given that A + B = C, and that lAl + lBl = lCl , how are vectors A and B oriented with respect to each other? a) they are perpendicular to each other b) they are parallel and in the same direction c) they are parallel but in the opposite direction d) they are at 45° to each other e) they can be at any angle to each other

b) they are parallel and in the same direction

A mass oscillates in simple harmonic motion with amplitude A. If the mass is doubled, but the amplitude is not changed, what will happen to the total energy of the system? a) total energy will increase b) total energy will not change c) total energy will decrease

b) total energy will not change

Suppose you are talking by interplanetary telephone to a friend, who lives on the Moon. He tells you that he has just won a newton of gold in a contest. Excitedly, you tell him that you entered the Earth version of the same contest and also won a newton of gold! Who is richer? 1. You are. 2. Your friend is. 3. You are equally rich.

b) your friend is

A 1-kg ball is hung at the end of a rod 1-m long. If the system balances at a point on the rod 0.25 m from the end holding the mass, what is the mass of the rod? a) ¼ kg b) ½ kg c) 1 kg d) 2 kg e) 4 kg

c) 1kg

A box is being pulled up a rough incline by a rope connected to a pulley. How many forces are doing work on the box? a) 1 b) 2 c) 3 d) 4

c) 3 gravity, friction, tension normal force doesn't do any work because it is perpendicular to the object

You are adding vectors of length 20 and 40 units. What is the only possible resultant magnitude that you can obtain out of the following choices? a) 0 b) 18 c) 37 d) 64 e) 100

c) 37 The minimum resultant occurs when the vectors are opposite, giving 20 units. The maximum resultant occurs when the vectors are aligned, giving 60 units. Anything in between is also possible for angles between 0° and 180°.

An automobile cannot maintain a constant velocity when A. accelerating. B. rounding a curve. C. Both of the above. D. None of the above.

c) Both

You kick a smooth flat stone out on a frozen pond. The stone slides, slows down, and eventually stops. You conclude that: a) the force pushing the stone forward finally stopped pushing on it b) no net force acted on the stone c) a net force acted on it all along d) the stone simply "ran out of steam" e) the stone has a natural tendency to be at rest

c) a net force acted on it all along

How does the work required to stretch a spring 2 cm compare with the work required to stretch it 1 cm? a) same amount of work b) twice the work c) four times the work d) eight times the work

c) four times the work PE = 1/2kX^2

You throw a ball straight up into the air. In addition to gravity, the ball feels a force due to air resistance. Compared to the time it takes the ball to go up, the time it takes to come back down is: a) smaller b) the same c) greater

c) greater the ball is constantly losing mechanical energy due to air resistance

If each component of a vector is doubled, what happens to the angle of that vector? a) it doubles b) it increases, but by less than double c) it does not change d) it is reduced by half e) it decreases, but not as much as half

c) it does not change

You drive around a curve in a narrow one-way street at 30 mph when you see an identical car heading straight toward you at 30 mph. You have two options: hit the car head-on or swerve into a massive concrete wall (also headon). What should you do? a) hit the other car b) hit the wall c) makes no difference d) get insurance!

c) makes no difference In both cases your momentum will decrease to zero in the collision. Given that the time Dt of the collision is the same, then the force exerted on YOU will be the same!! If a truck is approaching at 30 mph, then you'd be better off hitting the wall in that case. On the other hand, if it's only a mosquito, well, you'd be better off running him down...

A box sits in a pickup truck on a frictionless truck bed. When the truck accelerates forward, the box slides off the back of the truck because: a) the force from the rushing air pushed it off b) the force of friction pushed it off c) no net force acted on the box d) truck went into reverse by accident e) none of the above

c) no net force acted on the box Generally, the reason that the box in the truck bed would move with the truck is due to friction between the box and the bed. If there is no friction, there is no force to push the box along, and it remains at rest. The truck accelerated away, essentially leaving the box behind!!

The velocity of a typical projectile can be represented by horizontal and vertical components. Assuming negligible air resistance, the horizontal component along the path of the projectile A. increases. B. decreases. C. remains the same. D. Not enough information.

c) remains the same no horizontal force

Paul and Kathleen start from rest at the same time on frictionless water slides with different shapes. At the bottom, whose velocity is greater? a) P b) K c) same

c) same

Mike applied 10 N of force over 3 m in 10 seconds. Joe applied the same force over the same distance in 1 minute. Who did more work? a) mike b) joe c) same

c) same time is not a factor in work

An astronaut on Earth kicks a bowling ball and hurts his foot. A year later, the same astronaut kicks a bowling ball on the Moon with the same force. His foot hurts... a) more b) less c) the same

c) the same The masses of both the bowling ball and the astronaut remain the same, so his foot feels the same resistance and hurts the same as before.

From the same height (and at the same time), one ball is dropped and another ball is fired horizontally. Which one will hit the ground first? a) the "dropped" ball b) the "fired" ball c) they both hit at the same time d) it depends on how hard the ball was fired e) it depends on the initial height

c) they both hit at the same time

Which is stronger, Earth's pull on the Moon, or the Moon's pull on Earth? a) the Earth pulls harder on the Moon b) the Moon pulls harder on the Earth c) they pull on each other equally d) there is no force between the Earth and the Moon e) it depends upon where the Moon is in its orbit at that time

c) they pull on each other equally

When throwing a ball straight up, which of the following is true about its velocity v and its acceleration a at the highest point in its path? a) both v = 0 and a = 0 b) v is not 0, but a = 0 c) v = 0, but a is not 0 d) both v is not 0 and a is not 0 e) not really sure

c) v = 0, but a is not 0

Astronauts in the space shuttle float because: a) they are so far from Earth that Earth's gravity doesn't act any more b) gravity's force pulling them inward is cancelled by the centripetal force pushing them outward c) while gravity is trying to pull them inward, they are trying to continue on a straight-line path d) their weight is reduced in space so the force of gravity is much weaker

c) while gravity is trying to pull them inward, they are trying to continue on a straight-line path

A hole is drilled through the center of Earth and emerges on the other side. You jump into the hole. What happens to you ? a) you fall to the center and stop b) you go all the way through and continue off into space c) you fall to the other side of Earth and then return d) you won't fall at all

c) you fall to the other side of the Earth and then return You fall through the hole. When you reach the center, you keep going because of your inertia. When you reach the other side, gravity pulls you back toward the center. This is Simple Harmonic Motion!

A mass on a spring in SHM has amplitude A and period T. How long does it take for the mass to travel a total distance of 6A ? a) ½T b) ¾T c) 1¼T d) 1½T e) 2T

d) 1.5 T We have already seen that it takes one period T to travel a total distance of 4A. An additional 2A requires half a period, so the total time needed for a total distance of 6A is 1 T.

Carefully place a small rubber ball (mass m) on top of a much bigger basketball (mass M) and drop these from some height h. What is the velocity of the smaller ball after the basketball hits the ground, reverses direction, and then collides with the small rubber ball? a) zero b) v c) 2v d) 3v e) 4v

d) 3v

A fast-moving car hitting a haystack or hitting a cement wall produces vastly different results. Both experience A. the same change in momentum. B. the same impulse. C. the same force. D. A and B.

d) A and B Although stopping the momentum is the same whether done slowly or quickly, the force is very different.

A moving object has A. momentum. B. energy. C. speed. D. All of the above.

d) all of the above

By what factor does the kinetic energy of a car change when its speed is tripled? a) no change at all b) factor of 3 c) factor of 6 d) factor of 9 e) factor of 12

d) factor of 9

Antilock brakes keep the car wheels from locking and skidding during a sudden stop. Why does this help slow the car down? a) m k > m s so sliding friction is better b) m k > m s so static friction is better c) m s > m k so sliding friction is better d) m s > m k so static friction is better e) none of the above

d) m s > m k so static friction is better Static friction is greater than sliding friction, so by keeping the wheels from skidding, the static friction force will help slow the car down more efficiently than the sliding friction that occurs during a skid.

If two vectors are given such that A + B = 0, what can you say about the magnitude and direction of vectors A and B? a) same magnitude, but can be in any direction b) same magnitude, but must be in the same direction c) different magnitudes, but must be in the same direction d) same magnitude, but must be in opposite directions e) different magnitudes, but must be in opposite directions

d) same magnitude, but must be in opposite directions

A certain vector has x and y components that are equal in magnitude. Which of the following is a possible angle for this vector in a standard x-y coordinate system? a) 30° b) 180° c) 90° d) 60° e) 45°

e) 45 degrees The angle of the vector is given by tan q = y/x. Thus, tan q = 1 in this case if x and y are equal, which means that the angle must be 45°.

A mass on a spring in SHM has amplitude A and period T. What is the total distance traveled by the mass after a time interval T? a) 0 b) A/2 c) A d) 2A e) 4A

e) 4A In the time interval T (the period), the mass goes through one complete oscillation back to the starting point. The distance it covers is A + A + A + A (4A).

Which contributes more to the cost of your electric bill each month, a 1500- Watt hair dryer or a 600- Watt microwave oven? a) hair dryer b) microwave oven c) both contribute equally d) depends upon what you cook in the oven e) depends upon how long each one is on

e) depends on time

A mass on a spring in SHM has amplitude A and period T. At what point in the motion is v = 0 and a = 0 simultaneously? a) x = A b) x > 0 but x < A c) x = 0 d) x < 0 e) none of the above

e) none of the above

The Moon does not crash into Earth because: a) it's in Earth's gravitational field b) the net force on it is zero c) it is beyond the main pull of Earth's gravity d) it's being pulled by the Sun as well as by Earth e) none of the above

e) none of the above The Moon does not crash into Earth because of its high speed. If it stopped moving, it would, of course, fall directly into Earth. With its high speed, the Moon would fly off into space if it weren't for gravity providing the centripetal force.

If the amplitude of a simple harmonic oscillator is doubled, which of the following quantities will change the most? a) frequency b) period c) maximum speed d) maximum acceleration e) total mechanical energy

e) total mechanical energy Frequency and period do not depend on amplitude at all, so they will not change. Maximum acceleration and maximum speed do depend on amplitude, and both of these quantities will double. (You should think about why this is so.) The total energy equals the initial potential energy, which depends on the square of the amplitude, so that will quadruple.