Circular Motion V, A and F

A car is making a turn at speed v. The radius of the turn is r and the centripetal force on the car is F. If the car rounds the same curve at speed 2v, the required centripetal force is...

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NGSS.HS-PS2-1

A body of mass m moves in a horizontal circle of radius r at constant speed v for one complete revolution. Which of the following statements is incorrect?

• The angular velocity of body is directed perpendicular to the plane of circular motion

• The change in linear momentum of the body is zero

• The total energy of the body is constant.

A straight length of tape unwinds from a roll rotating about a fixed axis with constant angular velocity, the radius of the roll decreasing at a steady rate. Which of the following graphs correctly shows how the variation of speed v at which the tape moves away from the roll with time t?

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NGSS.HS-PS2-1

The clock on Big Ben has a minute hand of length 4.3 m and an hour hand of length 2.7 m. What is the ratio of the centripetal acceleration of a point on the tip of the minute hand to a point on the tip of the hour hand?

• 1.6

• 150

• 230

• 5700

Which of the following statements is not true for a stone attached to a string and swung in a uniform vertical circular motion?

• The magnitude of resultant force acting on the stone changes depending on the position of the stone in the circle.

• The tension in the string is lowest when the stone is at the highest point of the circular motion.

• The kinetic energy of the stone is constant throughout the entire circular motion.

• The resultant acceleration is always directed towards the centre of the circle.

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NGSS.HS-PS2-1

The combined mass of a race car and its driver is 600 kg. Travelling at constant speed, the car completes one lap around a circular track of radius 160 m in a total time of 36 s. What is the magnitude of the centripetal acceleration of the car?

• 0.17 m s^-2

• 4.9 m s^-2

• 100 m s^-2

• 2900 m s^-2

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NGSS.HS-PS2-1

In a tape cassette, the tape leaves one spool at a constant speed v and at a variable distance r from the centre. Which of the following statements is true?

• The angular velocity decreases as radius r decreases.

• The angular velocity increases as radius r decreases.

• The angular velocity is directly proportional to the speed v.

• The angular velocity is directly proportional to the speed v²

The maximum safe speed of a car rounding an unbanked corner is 16 m s^-1 when the road is dry. The maximum frictional force between the road surface and wheels of the car is halved when the road is wet. What is the maximum safe speed for the car to round the corner when the road is wet?

• 4.0 m s^-1

• 6.0 m s^-1

• 8.0 m s^-1

• 11 m s^-1

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NGSS.HS-PS2-1

A pendulum bob is released from rest in a horizontal position with the string taut. Which of the following statements is correct when the pendulum reaches its vertical position at point P?

• The tension attained its least value

• The tension depends only on the length of the pendulum

• The tension depends on the mass and length of the pendulum bob.

• The magnitude of tension equals the weight of the pendulum bob

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NGSS.HS-PS2-1

A rock attached to a string swings in a vertical circle. At the highest point,

• no forces act on the rock.

• only one force acts on the rock.

• two forces act on the rock and their resultant is zero.

• two forces act on the rock and their resultant is not zero.

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NGSS.HS-PS2-1