PHYS 201 Final Exam

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.

1.higher than it was before.

A component of a vector is _____ larger than the magnitude of the vector. 1.always 2.never 3.sometimes larger

2. never

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 lowestaverage 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

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.

2.Your friend is.

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.

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.No, both are the same. Explanation: 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.

When no air resistance acts on a fast-moving baseball, its acceleration is A.downward, g. B.due to a combination of constant horizontal motion and accelerated downward motion. C.opposite to the force of gravity.

A.downward, g.

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 distance apart.

There must be equal amounts of mass on both sides of the center of mass (or center of gravity) of a system. A) True B) False

B) False

Mike performed 5 Jof work in 10 secs. Joe did 3J of work in 5 secs. Who produced the greater power? A) Mike B) Joe C) Both produced the same amount of power

B) Joe

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. Explanation: The force on the cannonball will be the same for a short-or long barreled cannon. The longerbarrel provides for a longertime for the force to act and therefore a greater impulse.

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 orswerve into a massive concrete wall(also head-on). 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 of the collision is the same, then theforce exerted on YOUwill be the same!! If a truck is approaching at 30 mph, then you'd be better offhitting the wall in that case. On the other hand, if it's only a mosquito, well, you'd be better off running him down

Consider a high-speed bus colliding head-on with an innocent bug. The force of impact splatters the unfortunate bug over the wind shield. Which is greater, the force on the bug or the force on the bus? A.Bug. B.Bus. C.Both are the same. D.Cannot say.

C.Both are the same.

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

C.remains the same.

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

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.

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. Frictional force is a non-conservative force, so the leaf loses energy as it falls, and its final total energy is less than its initial total energy.

An object is rolling, so its motion involves both rotation and translation. Which one of the following statements must be true concerning this situation? a) The total mechanical energy is equal to the sum of the translational and rotational kinetic energies and the gravitational potential energy of the object. b) The translational kinetic energy may be equal to zero joules. c) The gravitational potential energy must be changing as the object rolls. d) The rotational kinetic energy must be constant as the object rolls.

a) The total mechanical energy is equal to the sum of the translational and rotational kinetic energies and the gravitational potential energy of the object.

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 (pushing) b) case 2 (pulling) 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 (pushing)

The disk shown below in (1)clearly has its center of mass at the center. Suppose the disk is cut in half and the pieces arranged as shown in (2). Where is the center of mass of (2) as compared to (1) ? a) higher b) lower c) at the same place d) there is no definable CM in this case

a) higher The CM of each half is closer to the top of the semicircle than the bottom. The CM of the whole system is located at the midpoint of the two semicircle CMs, which ishigherthan the yellow line.

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

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 complete revolution every 2 seconds. Kyle's angular velocity is: a) same as Bonnie's b) twice Bonnie's c) half of Bonnie's d) one-quarter of Bonnie's e) four times Bonnie's

a) same as Bonnie's The angular velocity of any point on a solid object rotating about a fixed axis is the same. Both Bonnie and Klydego around one revolution every 2 seconds.

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

For a given circle, the radian is defined as which one of the following expressions? a) the arc length divided by the radius of the circle b) (3.141592...) times twice the radius of the circle c) two times ninety degrees divided by (3.141592...) d) the arc length divided by the circumference of the circle e) the arc length divided by the diameter of the circle

a) the arc length divided by the radius of the circle

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

You are lying in bed and you want to shut your bedroom door. You have a superball and a blob of clay (both with the same mass) sitting next to you. Which one would be more effective to throw at your door to close it? a)The superball b)The blob of clay c)It doesn't matter they will be equally effective. d)You are just too lazy to throw anything.

a)The superball

Is it possible for the gravitational potential energy of an object to be negative? a)Yes b)No

a)Yes

If a spring has a spring constant of k=3 Newton's per meter (3 N/m), how much force is needed to stretch the spring 1.5m a)4 b) 4.5 c)5 d) 5.5

b) 4.5

A cart starting from rest rolls down a hill and at the bottom has a speed of 4m/s. If the cart were given an initial push, so its initial speed at the top of the hills as 3m/s, what would be its speed at the bottom? a) 4 m/s b) 5 m/s c) 6 m/s d) 7 m/s e) 25 m/s

b) 5 m/s

From rest, we step on the gas of your 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? a) 16 s b) 8 s c) 4 s d) 2 s e) 1 s

b) 8 s

If vector A is added to vector B, which the following choices must be true for the resultant vector to be equal to zero? a) B and A are parallel and in the same direction. b) B and A are parallel and in opposite directions. c) B and A are perpendicular.

b) B and A are parallel and in opposite directions.

Bonniesits on the outer rim ofa merry-go-round, and Klydesits 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 Their linear speeds vwill be different because v = r wand Bonnie is located farther out(larger radius r ) than Klyde

What can you say about the force of gravity Fg acting on a stone and a feather? a) Fg is greater on the feather b) Fg is greater on the stone c) Fg is zero on both due to vacuum d) Fg is equal on both always e) Fg is zero on both always

b) Fg is greater on the stone

A block of mass m rests on the floor of an elevator that is moving upward at constant speed. What is the relationship between the force due to gravity and the normal force on the block? a) N > mg b) N = mg c) N < mg (but not zero) d) N = 0 e) depends on the size of the elevator

b) N = mg

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

A ball is launched with an initial velocity V0 as shown. Which one of the following arrows best represents the direction of the acceleration at point B? a) right b) down c) right and up d) up e) The acceleration at point B is zero m/s2.

b) down

Complete the following statement; When determining the net torque on a rigid body, only the torques due to a) internal forces are considered. b) external forces are considered. c) forces that are either parallel or perpendicular to the lever arms are considered. d) forces that form action-reaction pairs, as in applying Newton's third law of motion, are considered. e) internal and external forces are considered.

b) external forces are considered.

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

b) false

You drive your dad's 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

Two spheres have the same radius and equal masses .One is made of solid aluminum, and the other is made from a hollow shell of gold. Which one has the bigger moment of inertia about an axis through its center? a) solid aluminum b) hollow gold c) same

b) hollow gold Moment of inertia depends on mass and distance from axis squared. It is bigger for the shell because its mass is located farther from the center.

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

Is the average speed of the red car a) more than 40 mph b) less than 40 mph c) 40 mph

b) less than 40 mph

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

b) no

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

b) no

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

b) no Because torque is the product of force times distance, two different forces that act at different distances could still give the same torque.

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 Momentum is a vector, so the fact that ptot= 0 does not mean that the particles are at rest! They could be moving such that their momenta cancel out when you add up all of the vectors. In that case, because they are moving, the particles would have non-zero KE.

You put your book on the bus seat next to you. When the bus stops suddenly, the book slides forward off the seat. Why? a) a net force acted on it b) no net force acted on it c) it remained at rest d) it did not move, but only seemed to e) gravity briefly stopped acting on it

b) no net force acted on it

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

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

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

b) speed

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) start to spin in the same direction as after flipping

b) start to spin in the same direction as before flipping The total angular momentum of the system is L upward,and it is conserved. So if the wheel has - L downward,you and the table must have 2L upward.

Ethan and Joseph are riding on a merry-go-round.Ethan rides on a horse at the outer rim of the circular platform, twice as far from the center of the circular platform as Joseph, who rides on an inner horse.When the merry-go-round is rotating at a constant angular speed,what is Ethan's angular speed? a) twice Joseph's b) the same as Joseph's c) half of Joseph's d) impossible to determine

b) the same as Joseph's

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

In a baseball game, the catcher stops a 90-mph pitch. What can you say about the work done by the catcher on the ball? a) Catcher has done positive work b)Catcher has done negative work c)Catcher has done zero work

b)Catcher has done negative work

A 1-kgball is hung at the end of a rod1-mlong. If the system balances at a point on the rod 0.25 mfrom the end holding the mass, what is the mass of the rod? a) ¼ kg b) ½ kg c) 1 kg d) 2 ag e) 4 kg

c) 1 kg The total torque about the pivot must be zero!!The CMof the rod is at its center, 0.25 mto the right of the pivot. Because this must balance the ball, which is the same distance to the left of the pivot, the masses must be the same !!

Two tug-of-war opponents each pull with a force of 100 N on opposite ends of a rope. What is the tension in the rope? a) 0 N b) 50 N c) 100 N d) 150 N e) 200 N

c) 100 N

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

In the game of tetherball, the struck ball whirls around a pole. In what direction does the net forceon the ball point? a) toward the top of the pole b) toward the ground c) along the horizontal component of the tension force d) along the vertical component of the tension force e) tangential to the circle

c) along the horizontal component of the tension force

Mike applied 10 N of force over 3 m in10 seconds. Joe applied the same force over the same distance in 1 minute. Who did more work? a) Mike b) Joe c) both did the same work

c) both did the same work

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 of the above

A small car collides with a large truck. Which experiences the greater impact force? a) the car b) the truck c) both the same d) it depends on the velocity of each e) it depends on the mass of each

c) both the same

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

c) both the same

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

Alice and Bill are at the top of a building. Alice throws her ball downward. Bill simply drops his ball. Which ball has the greater acceleration just after release? a) Alice's ball b) it depends on how hard the ball was thrown c) neither—they both have the same acceleration d) Bill's ball

c) neither—they both have the same acceleration

An open cart rolls along a frictionless track while it is raining. As it rolls, what happens to the speed of the cart as the rain collects in it?(Assume that the rain falls vertically into the box.) a) speeds up b) maintains constant speed c) slows down d) stops immediately

c) slows down Because the rain falls in vertically, it adds no momentum to the box, thus the box's momentum is conserved. However, because the mass of the box slowly increaseswith the added rain, its velocity has to decrease.

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

A box is being pulled up a rough incline by a rope connected to a pulley. How many forces are doing work on the red box? a) one force b) two forces c) three forces d) four forces e) no forces are doing work

c) three forces (tension, friction, weight)

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 does not = 0, but a = 0 c) v = 0, but a does not = 0 d) both v does not = 0 and a does not = 0 e) not really sure

c) v = 0, but a does not = 0

A hoop and a disk have the samemass and radius. The disk has half the moment of inertia of the hoop. If they start from rest at the top of a ramp, and if the reference for potential energy is at the bottom, which has the greater total energy? a)The hoop b)The disk c)The same

c)The same The mass of the two objects is the same and the only energy is potential, U, where: u = mgh. So, the two objects have the same total energy, which is of course ugh

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.

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 Explanation:Although stopping the momentum is the same whether done slowly or quickly, the force is very different..

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

A small cart is rolling at constant velocity on a flat track. It fires a ball straight up into the air as it moves. After it is fired, what happens to the ball? a) it depends on how fast the cart is moving 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

d) it falls right back into the cart

Two equal-mass particles (A and B) are located at some distance from each other. Particle A is held stationary while B is moved away at speed. What happens to the center of mass of the two-particle system? a) it does not move b) it moves away from A with speed v c) it moves toward A with speed v d) it moves away from A with speed ½v e) it moves toward A with speed ½v

d) it moves away from A with speed ½v

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

d) us> uk so static friction is better

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 youcook in the oven e) depends upon how long each one is on

e) depends upon how long each one is on