Angular displacement and angular velocityEdexcel International A Level Physics: Subtopic test

1. 1
   A fairground carousel rotates at a constant rate, making one complete revolution every 8.0 s. A child sits on a horse 4.0 m from the axis of rotation.

   (a)

   What is the angular velocity of the carousel?

   [1 mark]

   • A0.13 rad s⁻¹
   • B1.0 rad s⁻¹
   • C6.3 rad s⁻¹
   • D0.79 rad s⁻¹

   (b)

   What is the speed of the child?

   [1 mark]

   • A3.1 m s⁻¹
   • B0.79 m s⁻¹
   • C25 m s⁻¹
   • D6.3 m s⁻¹

   (c)

   Calculate the angle through which the child turns in 3.0 s, giving your answer in radians and in degrees.

   [2 marks]

   Total for question 1: 4 marks

2. 2
   A radar dish rotates at a constant rate, making 15 complete revolutions per minute. The controller divides each revolution into equal sectors, each covering 72°.

   (a)

   What is the angle of each sector in radians?

   [1 mark]

   • A0.40 rad
   • B5.0 rad
   • C1.26 rad
   • D226 rad

   (b)

   What is the angular velocity of the dish?

   [1 mark]

   • A0.25 rad s⁻¹
   • B1.6 rad s⁻¹
   • C94 rad s⁻¹
   • D15 rad s⁻¹

   (c)

   Calculate the period of rotation of the dish and the time taken for it to turn through one sector.

   [2 marks]

   Total for question 2: 4 marks

3. 3
   A hard disk drive platter of radius 4.7 cm spins at a constant 7200 revolutions per minute.

   (a)

   Calculate the angular velocity of the platter, the period of its rotation, and the speed of a point on its rim.

   [3 marks]

   (b)

   A block of data takes 2.0 ms to pass the read head. Calculate the angle in degrees through which the platter turns in this time, and explain why a point on the rim moves faster than a point near the centre.

   [4 marks]

   Total for question 3: 7 marks

4. 4
   A spin-dryer drum of radius 0.25 m rotates at a steady 1200 revolutions per minute.

   (a)

   Calculate the angular velocity of the drum, its period, the speed of a point on the drum wall, and the angle turned in 0.50 s in radians and in degrees.

   [6 marks]

   (b)

   A manufacturer designs a smaller drum of radius 0.18 m that also rotates at 1200 revolutions per minute. The wall of the drum must move at no less than 30 m s⁻¹. Evaluate whether the smaller drum meets this requirement, and calculate the angular velocity, in rad s⁻¹ and in revolutions per minute, needed if it does not.

   [6 marks]

   Total for question 4: 12 marks

End of questions