Page 25 - SP015 Past Years PSPM Chapter 6 -14 Ver 2020

PSPM SP015

PSPM 2011/2012 SF016/2 No. 5(c)

39.

P

h

Q

FIGURE 8.18

A solid sphere and a hollow sphere have the same mass, m and radius, r. FIGURE 8.18
shows both spheres are released simultaneously from rest at P and roll down on an
inclined plane. Which sphere will arrive first at Q? Show your answer. (Moment of
2
2
inertia of the spheres: I solid  2 5 mr and I hollow  2 3 mr ) [6 m]

PSPM 2012/2013 SF016/2 No. 5(b)

40. A disc rotates at 25 revolutions per minute and takes 15 s to come to rest. Calculate
(a) the angular acceleration of the disc. [2 m]
(b) the number of rotation the disc makes before it comes to rest. [2 m]
2
(c) the initial kinetic energy of the disc if its moment of inertia is 2.5 kg m . [3 m]

PSPM 2012/2013 SF016/2 No. 5(c)

41.

2 kg

FIGURE 8.19

FIGURE 8.19 shows a 2 kg box hung by a cord wound on a light pulley is released
2
from rest. The radius and the moment of inertia of the pulley are 0.25 m and 1.5 kg m .
Calculate the acceleration of the box. [6 m]

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