Page 80 - SP015 Past Years PSPM Chapter 6 -14 Ver 2020

PHYSICS PSPM SEM 1 1999 - 2017

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29. (a) L = 5.63 kg m s (b)  = 0.80 N m
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30. v = 1.9 m s
31. h max = 0.29 m
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32. (a) I = 0.25 kg m (b) L = 0.785 kg m s (c) K = 1.23 J
33. (b) a = 3.50 m s -2
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34. (a)  = –47.12 rad s (b) t = 4 s (c) K r = –888.3 J
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35. (a)  = 6 rad s (b) v = 1.2 m s
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36. (a) (i) U = 98.1 J (ii) v = 8.1 m s (iii) t = 2.47 s
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(b) Solid cylinder   = I = constant    Since I solid < I hollow   solid >  hollow
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37. (a) a = 7.36 m s (b) T = 7.36 N
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(c) (i) K r = 23.12 J (ii) L = 0.68 kg m s
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38. (a)  = 2.86 N m (b)  = 6.01 rad s (c)  = 2 rev
39. Solid sphere will arrive first at Q since v solid > v hollow .
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40. (a)  = 0.175 rad s (b)  = 3.12 rev (c) K i = 8.58 J
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41. a = 0.75 m s
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42. (a) I = 3.78  10 kg m (b) W = 3109 J
43. Solid sphere will reach the bottom of the slope first. When I , v 
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44. (a)  = 1.46 rad s (b) a = 1.54 m s (c) F = 92.4 N
(d) Travelling in a straight line, tangent to the circle the instant they let go.
45. t = 6.7 s
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46. (a)  = 6.3 rad s (b) t = 11.1 s (c) P = 2500 W
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47. (a)  = 1.2 N m (b)  = 0.71 rad s (c) a t = 1.07 m s -2
48. Angular momentum is the vector product between radius of rotation with the linear momentum. Angular
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momentum, L  r  p or L = I or L = mrv
49. L = constant in a closed system
50. The boiled egg will rotate longer because the yolk in the boiled egg is harden thus its moment of inertia is
constant.   L = I = constant and I is constant thus  is also constant.
The egg yolk in the raw egg is soft and mobile thus its moment of inertia will change when r changes.
  L = I = constant and I is large thus  will decrease.
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51. (a) I system = 82.3 kg m (b) L = 450 kg m s (c) W = 1230 J
(d) The platform will rotate faster.
52. r f = 36 cm
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53.  = 2.5 rad s

FINAL ANSWER FOR CHAPTER 9: SIMPLE HARMONIC MOTION

1. (a) Simple harmonic motion is a periodic motion of a body without loss of energy with its acceleration
directed towards the equilibrium point and proportional to the displacement from the equilibrium
point.
(b) No, because its acceleration is not proportional to its displacement.
2. The equation shows that acceleration of the motion is directly proportional to the displacement but
always in opposite direction.
3. Simple harmonic motion is a periodic motion without energy loss due to existence of restoring force and
absence of dissipative force.
4. Acceleration is directly proportional to the displacement of the object from the equilibrium position but
always in opposite direction.
Acceleration always point towards the equilibrium position.
5. A point is in circular motion. Projection of the moving point on any diameter is a simple harmonic
motion.
6. Force is proportional to the magnitude of displacement. Force is opposite direction to displacement.
7. The direction of acceleration in SHM is always opposite to displacement.
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8. (a)  = 4.19 rad s (b) v max = 0.84 m s
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9. E = 1.58  10 J, k = 0.12 N m
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10. (a) v = 2.83 m s (b) v = 2.11 m s (c) E = 2 J
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11. (a) T = 1.57 s (b) (i) v = –1.75 m s
(b) (ii) The body moves to the left towards the equilibrium point.
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