Physics Quiz 5 and 6

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 tangential speed?

Child A

If the Earth had four times its present mass, what would be its new period of revolution around the sun, compared to its present orbital period?

the same

To push a piece of heavy furniture across the carpet usually takes more force to get it moving than it takes to keep is moving. This is because

the static coefficient of friction is larger than the kinetic coefficient

A race car, traveling at a constant speed of 50 m/s, drives around a circular track of radius 250 m. What angular acceleration does it experience?

1.0 × 10^4 rad/s^2

The following statements refer to man-made, artificial satellites in orbit around Earth. Which is an accurate statement?

A satellite in a large diameter circular orbit will always have a longer period of revolution about the Earth than will a satellite in a smaller circular orbit.

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 centripetal acceleration?

Child A

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

The kinetic coefficient of friction is usually larger than the static coefficient of friction.

False

The net force on an object in orbit is zero.

False

When a rigid body rotates about a fixed axis all the points in the body have the same centripetal acceleration.

False

When a rigid body rotates about a fixed axis all the points in the body have the same linear displacement.

False

When a rigid body rotates about a fixed axis all the points in the body have the same tangential acceleration.

False

When a rigid body rotates about a fixed axis all the points in the body have the same tangential speed.

False

A spaceship is traveling to the moon. At what point is it beyond the pull of Earth's gravity?

It is never beyond the pull of Earth's gravity.

Satellite A has twice the mass of satellite T, and rotates in the same orbit. Which of the following is true?

The speed of T is equal to the speed of A.

(6.1 : #13) Marilyn (M) and her sister Sheila (S) are riding on a merry-go-round, as shown in Fig. 7-3 (bird's-eye view). Which of the following is true?

They have different speeds, but the same angular 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 angular displacement?

They have the same non-zero angular displacement.

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 angular speed?

They have the same non-zero angular speed.

When a rigid body rotates about a fixed axis all the points in the body have the same angular acceleration.

True

When a rigid body rotates about a fixed axis all the points in the body have the same angular displacement.

True

When a rigid body rotates about a fixed axis all the points in the body have the same angular speed.

True

A car, driven around a circle with constant speed, must have

a centripetal acceleration.

3) A toolbox, of mass M, is resting on a flat board, as shown in Fig. 4-5. One end of the board is lifted up until the toolbox just starts to slide. The angle θ that the board makes with the horizontal, for this to occur, depends on the

coefficient of static friction,mu

A pilot executes a vertical dive. Just before the plane starts to come up from the bottom of the dive, the force on him is

more than g, and pointing up.

Does the centripetal force acting on an object do work on the object?

no, because the force and the displacement of the object are perpendicular

A satellite encircles Mars at a distance above its surface equal to 3 times the radius of Mars. The acceleration of gravity at the satellite, as compared to the acceleration of gravity on the surface of Mars, is

one-sixteenth as much.

15) James is twirling a rock around a horizontal circle on the end of a string. Fig. 7-4 is a top view (motion is counterclockwise). If the speed is constant what is the acceleration at point A?

rv^2

A brick and a feather fall to the Earth at their respective terminal velocities. Which object experiences the greater force of air friction?

the brick

Consider a small satellite moving in a circular orbit (radius r) about a spherical planet (mass M). The period does not depend upon

the satellite mass.

An object is dropped from a helicopter. When it reaches terminal velocity

the total force is zero