Psysics 111 Multiple Choice

A boat that can travel at 4.0 km/h in still water crosses a river with a current of 2.0 km/h. At what angle must the boat be pointed upstream (that is, relative to its actual path) to go straight across the river?

30 degrees

Which of the following situations is not possible?

A body travels with a constant velocity and a non-zero acceleration

Which one of the following statements concerning vectors and scalars is false?

A vector that is zero may have components other than zero

Two children are riding on a merry-go-round. Child A is at a greater distance from the axis of rotation than child B. Which child has the smaller linear displacement?

Child B

In dimensional analysis, the dimensions for speed are

L/T

Which of the following quantities is a vector quantity

the sun's pull on earth

Complete the following statement: If positive work is done on a moving object

the velocity of the object will increase

Complete the following statement: For a wheel that turns with constant angular speed?

the wheel turns through equal angles in equal times

Which of the following cannot cause a car to have an acceleration?

the windshield wipers

Complete the following statement: A force that acts on an object is said to be conservative if

the work it does on the object is independent of the path of motion

Two private airplanes are taxiing at a small airport. Jim is in plane A rolling due south with respect to the ground. Samantha is in plane B rolling due west with respect to the ground. Samantha is in front of Jim and to his left. In what direction(s), relative to himself, does Jim see Samantha's plane moving?

to the northwest

A ladybug sits at rest on a turntable that is rotating with constant angular velocity. During this motion, the ladybug's acceleration vector points

toward the center of the turntable

Which of the following statements concerning unit conversion is false?

units have no numerical significance, so 1 meter can =1 foot

An automotive test driver travels due north in a prototype hybrid vehicle at 30 mi/h for 2 hours. She then reverses her direction and travels due south at 60 mi/h for 1 hour. What is the average velocity of the vehicle?

zero mi/hr

A motorcycle has a velocity of 24 m/s, due south as it passes a car with a velocity of 15 m/s, due north. What is the magnitude and direction of the velocity of the motorcycle as seen by the driver of the car?

39 m/s(sum of vectors)

The spring-loaded gun can launch projectiles at different angles with the same launch speed. At what angle should the projectile be launched in order to travel the greatest distance before landing?

45 degrees

A rock is whirled on the end of a string in a horizontal circle of radius R with a constant period T. If the radius of the circle is reduced to R/3, while the period remains T, what happens to the centripetal acceleration of the rock?

the centripetal acceleration increases by a factor of 3

The earth exerts the necessary centripetal force on an orbiting satellite to keep it moving in a circle at constant speed. Which statement best explains why the speed of the satellite does not change although there is a net force exerted on it?

the centripetal force is always perpendicular to the velocity

What does the word "normal" mean in the phrase "normal force"?

the component of the force exerted by a surface perpendicular to the surface

A force is applied to a doorknob. This force will be most effective in causing the door to rotate when which of the following is true?

the direction of the force in 90 degrees with respect to the door

In which one of the following circumstances does the force do negative work on the object?

the direction of the force is in the opposite direction to the object's displacement

A particle travels along a curved path between two points A and B as shown. Complete the following statement: The displacement of the particle does not depend on

the distance traveled from A to B

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 this force equals the weight of the fireman, what happens?

the fireman continues to descend, but with constant speed

The maximum speed at which a car can safely negotiate a frictionless banked curve depends on all of the following except

the mass

In an INELASTIC collision between two objects

the momentum of the system is conserved but the kinetic energy of the system is not conserved

An object is moving forward with a constant velocity. Which statement about this object MUST be true?

the net force on the object is zero

Angular momentum cannot be conserved if

the net torque is not zero

A boy throws a rock with an initial velocity of 2.15 m/s at 30.0° above the horizontal. If air resistance is negligible, how long does it take for the rock to reach the maximum height of its trajectory?

.11s (Vf^2=V0^2+At)

A stock person at the local grocery store has a job consisting of the following five segments: (1) picking up boxes of tomatoes from the stockroom floor (2) accelerating to a comfortable speed (3) carrying the boxes to the tomato display at constant speed (4) decelerating to a stop (5) lowering the boxes slowly to the floor. During which of the five segments of the job does the stock person do positive work on the boxes?

1 and 2

Which one of the following combinations of units is equal to the joule?

1 kgxm^2/s^2

Usain Bolt set a world record for the 100.0-m run with a time of 9.58 s. If, after reaching the finish line, Mr. Bolt walked directly back to his starting point in 90.9 s, what is the magnitude of his average speed for the 200.0 m?

1.99m/s

which of the following is the longest length?

10^4 millimeters

A ferry can travel at an optimal speed of 8 km/h in still water measured relative to the shore. What is the optimal speed of the ferry, relative to the shore, if it moves perpendicular to a 6 km/h current?

10km/hr

Referring to the triangle with sides labeled A, B, and C as shown, which of the following ratios is equal to the sine of the angle

A/C

Which of the following is true for an object in freefall, if we assume +y is in the upward direction?

All of these

Which of the following quantities is defined as the distance traveled divided by the elapsed time for the travel?

Average speed

An airplane starts from rest at the end of a runway and begins accelerating. The tires of the plane are rotating with an angular velocity that is uniformly increasing with time. On one of the tires, Point A is located on the part of the tire in contact with the runway surface and point B is located halfway between Point A and the axis of rotation. Which one of the following statements is true concerning this situation?

Both points have the same instantaneous velocity.

Two children are riding on a merry-go-round. Child A is at a greater distance from the axis of rotation than child B. Which child has the larger linear displacement?

Child A(further away from rotation greater linear displacement)

A rock is thrown at some angle above the horizontal with a certain velocity. It reaches its highest point and starts falling down. What is the velocity of the rock at the highest point of its trajectory?

It is equal to its initial horizontal velocity

Two football players, Ted and Jeff, with the same weight are climbing steps during practice. Ted completes one set of steps in 30 seconds, Jeff completes two sets of steps in 60 seconds. How does the power used by each player compare?

Jeff and Ted use the same amount of power

In dimensional analysis, the dimensions for acceleration are

L/T^2

You ride on an elevator that is moving with constant downward acceleration while standing on a bathroom scale. The reading on the scale is

Less than your true weight, mg

In which one of the following systems is there a decrease in gravitational potential energy?

My cat ozzie jumps down from bed and lands on his feet

Power may be expressed using all of the following units except:

N*m*s

A ping-pong ball moving east at a speed of 4 m/s, collides with a stationary bowling ball. The Ping-Pong ball bounces back to the west, and the bowling ball moves very slowly to the east. Which object experiences the greater magnitude impulse during the collision?

Neither; both experienced the same magnitude impulse.

A woman is straining to lift a large crate, without success because it is too heavy. We denote the forces on the crate as follows: P is the upward force the woman exerts on the crate, C is the vertical contact force exerted on the crate by the floor, and W is the weight of the crate. How are the magnitudes of these forces related while the woman is trying unsuccessfully to lift the crate?

P + C = W

Which of the following units is not an SI base unit

Slug

A ball is thrown vertically upward from the surface of the earth. The ball rises to some maximum height and falls back toward the surface of the earth. Which of the following statements concerning this situation is true if air resistance is neglected?

The ball is a freely falling body for the duration of its flight

s A ball rolls off the edge of a table. The horizontal component of the ball's velocity remains constant during its entire trajectory because

The ball is not acted upon a force in the horizontal direction

A bicycle racer is traveling at constant speed, v, around a circular track. The centripetal acceleration of the bicycle is ac. What happens to the centripetal acceleration of the bicycle if the speed is doubled to 2v?

The centripetal acceleration increases to 4ac.

The centripetal force is best explained by which of the following statements?

The centripetal force is the net force acting on an object that maintains it in uniform circular motion

In which one of the following circumstances does the force do positive work on the object?

The direction of the force is in the same direction as the object's displacement

Which one of the following statements concerning kinetic energy is true?

The kinetic energy is always positive

A lightweight crate and a heavy crate are side-by-side on a horizontal floor. You apply a horizontal force to the lightweight crate. There is friction between the crates and the floor. If the two crates are accelerating to the right,

The lightweight crates exerts as much force on the heavy crate as the heavy crates exerts on the light crate

A collision between two objects is inelastic. Which one of the following statements concerning this situation is true?

The objects stick together and move as one after the collission

A collision between two objects is elastic. Which one of the following statements concerning this situation is true?

The total kinetic energy of the objects is the same before and after the collision.

An object is rolling, so its motion involves both rotation and translation. Which of the following statements must be true concerning this situation?

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

For an object in uniform circular motion, which one of the following statements is false?

The velocity of the object is constant.

A baseball is hit upward and travels along a parabolic arc before it strikes the ground (so air resistance can be neglected). Which one of the following statements is necessarily true?

The x component of the velocity of the ball is the same throughout the ball's flight

In two-dimensional motion in the x-y plane, what is the relationship between the x part of the motion to the y part of the motion?

The x part of motion is independent of the y part of motion

Consider what happens when you jump up in the air. Which of the following is the most accurate statement?

When you push down on the earth with a force greater than your weight, the earth will push back with the same magnitude force and thus propel you into the air.

You are trying to hit a friend with a water balloon. He is sitting in the window of his dorm room directly across the street (you are at the same height). You aim straight at him and shoot. Just when you shoot, he falls out of the window! Assuming the balloon has a large enough horizontal velocity component to reach the building, does the water balloon hit him?

Yes

A packing crate slides down an inclined ramp at constant velocity. Thus we can deduce that

a frictional force is acting on it

A passenger at rest on a flatbed train car fires a bullet straight up. The event is viewed by observers at rest on the station platform as the train moves past the platform with constant velocity. What is the trajectory of the bullet as described by the observers on the platform?

a parabolic path

Which of the following can cause a car to have an acceleration?

a. brakes on the car and the steering wheel(b)

The momentum of an object is not dependent on which one of the following quantities?

acceleration

Which of the following statements concerning vectors and scalars is true?

all of these

Which one of the following situations does the object have no acceleration?

an elevator in a tall skyscraper moves upward at a constant speed of 3 m/s

Which one of the following is not a vector quantity?

average speed

You are standing on a skateboard, initially at rest. A friend throws a very heavy ball towards you. You can either catch the object or deflect the object back towards your friend (such that it moves away from you with the same speed as it was originally thrown). What should you do in order to MINIMIZE your speed on the skateboard?

catch the ball

You are standing on a skateboard, initially at rest. A friend throws a very heavy ball towards you. You can either catch the object or deflect the object back towards your friend (such that it moves away from you with the same speed as it was originally thrown). What should you do in order to Maximize your speed on the skateboard?

deflect the ball

You swing a bat and hit a heavy box with a force of 1500 N. The force the box exerts on the bat is

exactly 1500 whether or not the box moves

Complete the following statement: When determining the net torque on a rigid body, only the torques due to

external forces are considered

An object hits a wall and bounces back with half of its original speed. What is the ratio of the final kinetic energy to the initial kinetic energy?

final =1 initial=4

A flatbed truck is carrying a crate along a level road. The coefficient of static friction between the load and the bed is 0.40. The truck accelerates forward and the crate stays in its place on the truck bed. In what direction is the force that the bed exerts on the crate?

forward

Because Earth's orbit is slightly elliptical, Earth actually gets closer to the Sun during part of the year. When Earth is closer to the Sun its orbital speed is

greater when close to sun;slower when further away

A person sits on a freely spinning lab stool (no friction). When this person extends her arms,

her moment of inertia increases and her angular velocity decreases

A train leaves a station, starting from rest, at time t = 0.0 s. At time t = 3600.0 s, the train is traveling due west at 28 m/s. In this example, the 28 m/s is the train's

instantaneous speed

The speedometer on a car's dashboard measures which of the following quantities?

instantaneous speed

Which of the following is the shortest length

micrometers(1 micrometer= 1x10-6 meters)

A projectile is launched at a 30° angle above the horizontal. Ignore air resistance. The projectile's acceleration is greatest

misleading question the acceleration is the same(but nonzero) at all points of trajectory

In an Elastic collision between two objects

momentum and kinetic energy are conserved

An artillery shell explodes in midair and breaks up into many fragments. Which of the following statements are true regarding conditions immediately before and immediately after the explosion: I. The total momentum of the fragments is equal to the original momentum of the shell. II. The total kinetic energy of the fragments is equal to the original kinetic energy of the shell.

momentum at the beginning is equal to momentum at the end

A student kicks a soccer ball in a high arc (not straight up) toward the opponent's goal. At the highest point in its trajectory:

neither the ball's velocity nor its acceleration is zero

Suppose you are playing hockey on a new-age ice surface for which there is no friction between the ice and the hockey puck. You wind up and hit the puck as hard as you can. After the puck loses contact with your stick, the puck will

not slow down or speed up

A block is pulled up an incline with a constant acceleration by a force, P. What is the direction of the kinetic friction force?

parallel to the incline and opposite to P

t of 1 points You drop a package from a plane flying at constant speed in a straight line. Without air resistance, the package will:

remain vertically under the plane while falling

Two pucks on an air hockey table collide elastically. Complete the following statement: when such a collision occurs in two dimensions, the before and after velocities are best determined by

remembering the momentum is a vector quantity that is conserved in each direction.

Alice and Tom dive from an overhang into the lake below. Tom simply drops straight down from the edge, but Alice takes a running start and jumps with an initial horizontal velocity of 25 m/s. Neither person experiences any significant air resistance. Compare the time it takes each of them to reach the lake below.

same time

Which of the following units cannot be added together, even if the proper conversions are made?

seconds and slugs

A disk, a hoop, and a solid sphere are released at the same time at the top of an inclined plane. They all roll without slipping. In what order do they reach the bottom?

sphere, disk, hoop

A string is attached to the rear-view mirror of a car. A ball is hanging at the other end of the string. The car is driving around in a circle, at a constant speed. Which of the following lists gives all of the forces directly acting on the ball?

tension and gravity

A ball moves in a circular path on a horizontal, frictionless surface. It is attached to a light string that passes through a hole in the center of the table. If the string is pulled down, thereby reducing the radius of the path of the ball, the speed of the ball is observed to increase. Which one of the following statements provides an explanation for this increase?

the angular momentum of the ball is conserved in the process

A child standing on the edge of a freely spinning merry-go-round moves quickly to the center. Which one of these statements is necessarily true if there is no friction involved and why?

the angular speed of the system increases because the moment of inertia has decreased

A rubber ball and a lump of putty have equal mass. They are thrown with equal speed against a wall. The ball bounces back with nearly the same speed with which it hit. The putty sticks to the wall. Which objects experiences the greater momentum change?

the ball greater and the putty lesser

Which one of the following statements concerning the principle of conservation of energy is false?

the net work done on an object must be zero joules since energy is neither created nor destroyed in the process

Complete the following statement: The center of mass is

the point within an object that moves as if all of the object's mass were located there.

Starting from rest, a particle that is confined to move along a straight line is accelerated at a rate of 5.0 m/s2. Which statement concerning the slope of the position versus time graph for this particle is true?

the slope is not constant and increases with increasing time

A space shuttle is in orbit around the earth at an altitude of 12,000 miles. Which one of the following statements best explains why the astronauts experience "weightlessness?"

the space ship is in free fall; and its floor cannot press upwards on the astronauts

A box slides down a frictionless plane inclined at an angle θ above the horizontal. The gravitational force on the box is directed

vertically