6.0 CIRCULAR MOTION

If a wheel turns with constant angular speed then:

• each point on its rim moves with constant velocity

• each point on its rim moves with constant acceleration

• the wheel turns through equal angles in equal times

• the angle through which the wheel turns in each second increases as time goes on

• the angle through which the wheel turns in each second decreases as time goes on

Consider an object on a rotating disk a distance r from its center, held in place on the disk by static friction. Which of the following statements is not true concerning this object?

• If the angular speed is constant, the object must have constant tangential speed

• If the angular speed is constant, the object is not accelerated.

• The object has a tangential acceleration only if the disk has an angular acceleration.

• If the disk has an angular acceleration, the object has both a centripetal and a tangential acceleration.

• The object always has a centripetal acceleration except when the angular speed is zero.

Merry-go-round rotates with constant angular speed. As a rider moves from the rim of the merry-go-round toward the center, what happens to the magnitude of total centripetal force that must be exerted on him?

• It increases.

• It is not zero, but remains the same.

• It decreases.

• It’s always zero.

• It increases or decreases, depending on the direction of rotation.

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NGSS.HS-PS2-1

A satellite moves in a circular orbit at a constant speed around Earth. Which of the following statements is true?

• No force acts on the satellite.

• The satellite moves at constant speed and hence doesn’t accelerate.

• The satellite has an acceleration directed away from Earth.

• The satellite has an acceleration directed toward Earth.

• Work is done on the satellite by the force of gravity.

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NGSS.HS-PS2-1

NGSS.HS-PS2-4

Which of the following statements are true of an object in orbit around Earth?

• If the orbit is circular, the gravity force is perpendicular to the object’s velocity

• If the orbit is elliptical, the gravity force is parallel to the velocity vector only at the nearest and farthest points.

• If the orbit is not circular, the speed is greatest when the object is farthest away from Earth.

• The gravity force on the object always has components both parallel and perpendicular to the object’s velocity.

• All these statements are true

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NGSS.HS-PS2-1

NGSS.HS-ESS1-4

NGSS.HS-PS2-4

An object moves in a circular path with constant speed v. Which of the following statements is true concerning the object?

• Its velocity is constant, but its acceleration is changing.

• Its acceleration is constant, but its velocity is changing.

• Both its velocity and acceleration are changing.

• Its velocity and acceleration remain constant.

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NGSS.HS-PS2-1

moving or tending to move toward a center...

• centripetal force

• centrifugal force

• Tangent

• Curvature

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NGSS.MS-PS2-2

Which represents the acceleration of the ball?

• A
• B
• C
• D

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NGSS.HS-PS2-1

Which of the following depict the speed of the blowing ball?

• A
• B
• C
• D

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NGSS.MS-PS3-1

A ball on a string is spun around in a circle. Which of the following quantities is not constant?

• mass

• force

• velocity

• acceleration