Rotational Motion

You are making a circular turn in your car on a horizontal road when you hit a big patch of ice, causing the force of friction between the tires and the road to become zero. While the car is on the ice, it

• continues to follow a circular path, but with a radius larger than the original radius.
• moves along a straight-line path toward the center of the circle.
• moves along a straight-line path away from the center of the circle
• moves along a straight-line path in its original direction.

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NGSS.HS-PS2-1

NGSS.HS-PS2-2

When a car goes around a circular curve on a horizontal road at constant speed, what force causes it to follow the circular path?

• the normal force from the road
• gravity
• the friction force from the road
• No force causes the car to do this because the car is traveling at constant speed and therefore has no acceleration.

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NGSS.HS-PS2-1

If a coin is rotating clockwise in a circular path on a turntable, which of the following is true?

• when the coin is at the top of the turntable, the acceleration is pointing to the left
• when the coin is at the bottom of the turntable the velocity points towards the center.
• the force keeping the coin in place is the weight of the coin pointing towards the center
• the acceleration of the coin is caused by a frictional force pointing towards the center 

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NGSS.HS-PS2-1

A car goes around a circular curve on a horizontal road at constant speed. What is the direction of the friction force on the car due to the road?

• tangent to the curve in the forward direction
• perpendicular to the curve outward
• perpendicular to the curve inward
• tangent to the curve opposite to the direction of the car's motion

When an object moves in uniform circular motion, the direction of its acceleration is

• in the same direction as its velocity vector.
• is directed toward the center of its circular path.
• in the opposite direction of its velocity vector.
• depends on the speed of the object.

A 1000-kg car is moving at 30 m/s around a horizontal unbanked curve whose diameter is 0.20 km. What is the magnitude of the friction force required to keep the car from sliding?

• 9000 N
• 300 N
• 9800 N
• 900 N

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NGSS.HS-PS2-1

A 0.50-kg toy is attached to the end of a 1.0-m very light string.  The toy is whirled in a horizontal circular path on a frictionless tabletop.  If the maximum tension that the string can withstand without breaking is 350 N.  What is the maximum speed the mass can have without breaking the string?

• 700 m/s
• 26 m/s
• 13 m/s
• 19 m/s

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NGSS.HS-PS2-1

Jack and Rose are holding hands and spinning in a circle as fast as they can. If rose lets go on accident, what can you say about Jack's motion.

• it will be in a straight line opposite of Rose
• it will be in a straight line in the direction of the instantaneous velocity
• it will be in a curved path in the direction that he was originally going
• Rose said she would never let go... she lied

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A jet plane flying 600 m/s experiences an acceleration of 4.0g (4 times that of gravity) when pulling out of a circular dive.  What is the radius of curvature of the circular part of the path in which the plane is flying?

• 7100 m 
• 640 m 
• 1200 m
• 9200 m 

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NGSS.HS-PS2-1

Which of the following is not a centripetal force?

• tension
• rotational
• normal force
• friction