Circular Motion

A 0.50 kilogram object moves in a horizontal circular path with a radius of 0.25 meter at a constant speed of 4.0 meters per second. What is the magnitude of the object’s acceleration?

• 8 m/s²

• 32 m/s²

• 16 m/s²

• 64 m/s²

Tags

NGSS.HS-PS2-1

A rider is on a Ferris wheel, traveling at a constant speed. Which force varies in magnitude as the ride turns, if any?

• Force of gravity

• Normal force

• Net centripetal force

• No force varies, they are all constant

Answer explanation

When traveling on a Ferris wheel, we must have more forces pointing in than out.

At the bottom, this means that normal force must be greater than force of gravity.

At the top, this means force of gravity must be greater than normal force.

Force of gravity doesn't change (it's mass x gravity). So, it's our normal force that will vary.

A rider is traveling around a Ferris wheel with a constant speed. Which of the following is constant and which isn't?

Groups:

(a) Constant

,

(b) Non-constant

• Velocity

• Kinetic energy

• Normal force

• Speed

• Net centripetal force

• Gravitational potential energy

A 2000 kilogram car travels at a constant speed of 12 meters per second around a circular curve of radius 30 meters. What is the magnitude of the centripetal acceleration of the car as it goes around the curve?

• 0.4 m/s²

• 800 m/s²

• 4.8 m/s²

• 9600 m/s²

If the velocity of a car traveling around a circular track doubles, its centripetal acceleration would be

• 1/2 as great

• 1/4 as great

• 2 times greater

• 4 times greater

In the diagram below, a cart travels clockwise at constant speed in a horizontal circle.

At the position shown in the diagram, which arrow indicates the direction of the centripetal acceleration of the cart?

• A

• B

• C

• D

Tags

NGSS.HS-PS2-1

In the diagram below, a cart travels clockwise at constant speed in a horizontal circle.

At the position shown in the diagram, which arrow indicates the direction of the velocity of the cart?

• A

• B

• C

• D

An unbalanced force of 40 Newtons keeps a 5 kilogram object traveling in a uniform circle of radius 2 meters. What is the speed of the object?

• 8 m/s

• 16 m/s

• 2 m/s

• 4 m/s

Answer explanation

Net centripetal force = mv2/r

If a rubber stopper completes 20 revolutions in 10 seconds, what is the period?

• 0.5 s

• 2 s

• 10 s

• 20 s

Answer explanation

The period, T, is how long it takes to make one rotation.

We do:

Total time / # of rotations

A car travels at a constant speed in a uniform circle. If the radius of the path is halved while maintaining the same speed, what happens to the centripetal acceleration

• Halved

• Doubled

• Quadrupled

• Remains the same

Answer explanation

ac = v² /r

centripetal acceleration is inversely proportional to radius