Page 28 - SP015 Past Years PSPM Chapter 6 -14 Ver 2020

PHYSICS PSPM SEM 1 1999 - 2017

Principle of Conservation of Angular Momentum

PSPM 2017/2018 SF016/2 No. 5(a)(ii)

48. Define angular momentum. [1 m]

PSPM JUN 1999/2000 SF025/2 No. 9(a)

49. State the principle of conservation of angular momentum. [2 m]

PSPM JAN 1999/2000 SF025/2 No. 10(d)

50. A raw egg and a boiled egg are let to rotate initially on a similar axis with the same
angular velocity. Explain which egg will rotate longer. [3 m]

PSPM JUN 1999/2000 SF025/2 No. 9(b)

51.

axis of rotation

2.0 m O X
1.2 m
F
platform

FIGURE 8.22

FIGURE 8.22 shows a 1.6 kg cat X at 1.2 m apart from the axis of rotation through
point O on the platform that rotates horizontally without friction. The platform has
2
moment of inertia 80.0 kg m and radius 2.0 m. It is rotating under a tangential force F
of constant magnitude 25.0 N.

(a) What is the moment of inertia for the whole rotating system? [2 m]

(b) If the platform starts to rotate from rest, what is the angular momentum of the
system after 9.0 s? [5 m]

(c) Calculate the work done on the platform in 9.0 s. [3 m]

(d) After 9.0 s, force F is taken out so that the platform and the cat rotate with a
constant angular velocity. What is the change that occurs to the platform if the cat
moves towards point O? Give reason to your answer. [3 m]

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