Lesson 3.6.1.1

3.6.1.1 Circular motion Quiz: AQA Physics, Unit 6

20 questions

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Lesson 3.6.1.1, Circular motion: 20 multiple choice questions for the AQA Physics (7408), Unit 6: Further mechanics and thermal physics (A-level only), written with Revision Ninja.

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The 20 questions

  1. The centripetal acceleration of an object moving in a circle of radius r at speed v is:

    • a = v^2 r
    • a = v^2 / r
    • a = v / r
    • a = r / v^2
  2. The direction of the centripetal force on an object moving in a circle is:

    • away from the centre of the circle
    • outwards from the rotation axis
    • towards the centre of the circle
    • along the tangent to the path
  3. The angular speed omega of an object moving with frequency f is:

    • omega = pi f
    • omega = 2 pi f
    • omega = 2 f r
    • omega = f / (2 pi)
  4. One radian is the angle subtended at the centre of a circle by an arc:

    • of 360 degrees
    • equal to a right angle
    • whose length equals the radius
    • whose length equals the circumference
  5. The centripetal force on an object of mass m moving at speed v in a circle of radius r is:

    • F = m v / r
    • F = m v^2 r
    • F = m v^2 / r
    • F = m v r
  6. Why does an object moving at constant speed in a circle have an acceleration?

    • its speed increases steadily
    • it experiences a constant force along its path
    • its velocity changes direction continuously
    • its kinetic energy changes
  7. The SI unit of angular speed is:

    • rad s^-1
    • rad m^-1
    • s^-1 m^-1
    • m s^-1
  8. A car travels round a bend of radius 50 m at 20 m/s. What is its centripetal acceleration?

    • 20 m s^-2
    • 2.5 m s^-2
    • 8 m s^-2
    • 0.4 m s^-2
  9. A 0.50 kg mass on a string of radius 1.2 m moves in a horizontal circle at 3.0 m/s. What is the tension in the string?

    • 1.25 N
    • 7.5 N
    • 0.94 N
    • 3.75 N
  10. A point on a rotating disc completes 2.0 revolutions per second at radius 0.25 m. What is its centripetal acceleration?

    • about 39 m s^-2
    • about 79 m s^-2
    • about 3.1 m s^-2
    • about 12.6 m s^-2
  11. A wheel rotates at frequency 4.0 Hz. What is its angular speed?

    • 50 rad s^-1
    • 8.0 rad s^-1
    • 25 rad s^-1
    • 2.0 rad s^-1
  12. A 2.0 kg object moves in a horizontal circle of radius 0.80 m at angular speed 5.0 rad/s. What is the centripetal force?

    • 10 N
    • 20 N
    • 80 N
    • 40 N
  13. A bicycle wheel of radius 0.35 m rotates at 3.0 revolutions per second. What is the speed of a point on its rim?

    • 1.1 m s^-1
    • 6.6 m s^-1
    • 21 m s^-1
    • 3.3 m s^-1
  14. For an object in circular motion, if its speed doubles but the radius stays the same, the centripetal force becomes:

    • unchanged
    • four times as great
    • half as great
    • twice as great
  15. A ball on a string is whirled at constant speed. If the radius is doubled and speed kept the same, the centripetal force:

    • halves
    • is unchanged
    • quadruples
    • doubles
  16. A particle travels 2.0 m along a circular path of radius 0.50 m. What angle, in radians, does it sweep through?

    • 1.0 rad
    • 0.25 rad
    • 2.5 rad
    • 4.0 rad
  17. A 0.20 kg ball on a 0.60 m string is whirled horizontally at 2.0 revolutions per second. What is the tension?

    • about 19 N
    • about 38 N
    • about 6.3 N
    • about 3.8 N
  18. A 1000 kg car goes round a flat bend of radius 40 m. Friction supplies at most 5000 N. What is the maximum speed without skidding? Give the value to one decimal place.

    • 10 m s^-1
    • about 14.1 m s^-1
    • 7.9 m s^-1
    • 20 m s^-1
  19. A student says a ball moving in a horizontal circle at constant speed has zero acceleration. Which response is best?

    • Correct: constant speed means there is no acceleration at all.
    • Incorrect: its velocity changes direction, so it has a centripetal acceleration towards the centre.
    • Correct, because centripetal force does no work so there is no acceleration.
    • Incorrect, because the acceleration is always tangential to the path.
  20. Objects A and B have the same angular speed. B moves in a circle of twice the radius of A. What is the ratio a_B / a_A of their centripetal accelerations?

    • 1
    • 2
    • 1/2
    • 4

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