Physics 211 Multiple Choice Final Prep

An object of mass 1g is whirled in a horizontal circle of radius 0.5m at a constant speed of 2 m/s. The work done on the object during one revolution is:

0

Newton's 3rd Law

Action-Reaction

An object rests on a horizontal frictionless surface. A horizontal force of magnitude F is applied. This force produces an acceleration

Always

Relationship between weight and mass

As mass increases, so does weight

Uniform Circular Motion

Constant speed but constantly changing direction

A car experiences both a centripetal and a tangential acceleration. For which would this be true?

It is going around a curve and slowing down

Elastic Collision

KE and Momentum both conserved

Which is a vector quantity (mass, density, speed, temperature)?

None, all are scalar

A cart loaded with sand slides along a horizontal frictionless track. As the cart moves, sand trickles out at a constant speed through a hole in the back of the cart. The speed of the cart will:

Remain the same because the sand is falling vertically

Two skiers start at the same place and finish at the same place. Skier A takes a straight route to the finish whereas Skier B takes a curvy route to the finish. If you assume that friction is negligible, which of the following statements is true?

Skier A has the same speed as Skier B at the finish. Length of route doesn't matter for velocity or speed.

An object moves in a circle at constant speed. The work done by the centripetal force is zero because

The displacement for each revolution is 0

A passenger elevator lifts a given load from the first floor to the tenth in less time than it takes for a freight elevator to do the same lift

The freight elevator operates at a lower power level

A force F, larger than the largest possible force of static friction, is applied to the left to an object moving to the right on a horizontal surface. That means:

The object must be slowing down

Two bodies of unequal mass, placed at rest on a frictionless surface, are acted on by equal horizontal forces for equal times. Just after these forces are moved, the body greater mass will have:

The same momentum as the other body

Two identical cylindrical disks have a common axis. Initially one of the disks is spinning. When the two disks are brought into contact, they stick together. What is true?

The total angular momentum is unchanged, and the total kinetic energy is reduced to one-quarter of its original value

The larger the orbital radius of a satellite, the longer its orbital period

True

The momentum of an object at a given instant is independent of its

acceleration

Centripetal acceleration

acceleration directed toward the center of the circle

An elevator is rising at constant speed:

acceleration is zero, the upwards cable force is constant, the kinetic energy is constant

A 10kg block of ice is at rest on a frictionless horizontal surface. A 1N force is applied in an easterly direction for 1s. During this time interval, the block:

acquires a momentum of 1.0 kg m/s

A baseball is hit high into the upper bleachers of left field. Over its entire flight the work done by gravity and the work done by air resistance, respectively, are

both negative

Which best describes the tangential acceleration of a cart moving at constant speed in a horizontal circle?

constant and directed radially toward the center of the curvature

As the distance between two masses increases, the gravitational force of attraction between them

decreases

Centripetal changes

direction

Which of the following groups does not contain a scalar quantity?

displacement, acceleration, force

If the mass of the cart was doubled, the magnitude of the centripetal force on the cart would be

doubled

A student's life was saved in an automobile accident because an airbag expanded in front of his head. If the car had not been equipped with an airbag, the windshield would have stopped the motion of his head in a much shorter time. Compared to the windshield, the airbag:

exerts a much smaller force over a greater time

In raising an object to a given height by means of an inclined plane, as compared with raising the object vertically, there is a reduction in

force required

Two objects are traveling around different circular orbits with constant speed. They both have the same acceleration but Object A is traveling twice as fast as Object B. The orbit radius for Object A is ______________ the orbit for Object B

four times

A stone is tied to a string and whirled at constant speed in a horizontal circle. The speed is then doubled without changing the length of the string. Afterward, the magnitude of the acceleration of the stone is:

four times as great

If the radius of the curvature of the path was doubled, the magnitude of the centripetal of the cart would be

halved

An object moving in a circle at constant speed

has an acceleration of constant magnitude

Tension forces are applied to a bone. If the stress caused by these forces is between the linear and elastic limits, when the tension is removed, the bone will

have its original unstretched length

Which of the following is not an example of accelerated motion?

horizontal component of projectile motion

As the time taken for a car to make one lap around a circular track decreases, the centripetal acceleration of the car

increases

The term "mass" refers to the same physical concept as

inertia

The mass of a body

is independent of the acceleration due to gravity

A body at rest is capable of doing work if:

it is free to move in such a way as to decrease its potential energy

A force on a particle is conservative if

its work depends on the end points of the motion, the the path between

The amount of work required to stop a moving object is equal to the

kinetic energy of the object

An event in which an isolated particle at rest breaks up into two different particles, only one of which remains at rest, would be extremely surprising because

linear momentum cannot be conserved in such a decay

Two objects interact with each other and with no other objects. Initially object A has a speed of 5m/s and object B has a speed of 10 m/s. In the course of their motion they return to their initial positions. Then A has a speed of 4m/s and B has a speed of 7m/s. We can conclude that:

mechanical energy was decreased by nonconsecutive forces

A block is suspended from a rope. The tension in the rope will be greatest when the block:

moves downward with decreasing speed

A physics textbook is suspended on a spring scale in an elevator. Of the following, the scale shows the highest reading when the elevator

moves downward with decreasing speed OR moves upward with increasing speed

A nonconsecutive force

none of the above

Which of the following five objects requires the greatest change in momentum to stop moving?

oil tanker

A particle moves at constant speed in a circular path. The instantaneous velocity and instantaneous acceleration vectors are:

perpendicular to each other

The work done by gravity during the descent of a projectile is

positive

The woundup spring of a clock possessess

potential but no kinetic energy

A ball is thrown into the air. As it rises there is an increase in its

potential energy

If two different masses have the same kinetic energy, their momenta are:

proportional to the square roots of their masses

A brick slides on a horizontal surface. Which of these will increase the frictional force on it?

putting a second brick on top

If the speed of the cart was doubled, the magnitude of the centripetal force on the cart would be

quadrupled

A woman lifts a barbell 2m in 5s. If she lifts is the same distance in 10s, the work done by her is

same distance, same work

Tangential changes

speed

A fast car hits the back of a truck moving in the same direction and they become locked together. If frictional forces with the road surface are negligible

the centre of mass will continue to move with the same velocity

Centripetal force

the force needed to keep an object moving in a circular path. Is a vector.

The law of conservation of momentum applies to a system of colliding objects only if

the net external impulse is zero

A feather and a lead ball are dropped from rest in a vacuum on the moon. The acceleration of the feather is

the same as that of the lead ball

A block is first placed on its long side and then on its short side on the same inclined plane. The block slides down the plant on its short side but remains at rest on its long side. A possible explanation is:

the short side is smoother

Mass differs from weight in that

weight is a force and mass is not

A kilowatt hour is a unit of

work

A heavy steel ball is suspended by a cord from a block of wood. The entire system is dropped through the air. Neglecting air resistance, the tension in the cord is:

zero

The torque exerted on a spinning, perfectly spherical and uniform density orbiting communications satellite by the gravitational pull of the earth is

zero