Page 33 - SP015 Past Years PSPM Chapter 1 -5 Ver.2020
P. 33
PSPM SP015
PSPM 2006/2007 SF017/2 No. 10(a)
15.
F
52
FIGURE 4.10
FIGURE 4.10 shows a 0.2 kg eraser being pressed against a whiteboard by a force F
inclined at 52 to the whiteboard. The coefficient of static friction,
between the eraser
and the whiteboard is 0.3.
(a) Draw a free body diagram to show all the forces acting on the eraser. [4 m]
(b) Calculate the the force F needed just to keep the eraser from sliding down. [4 m]
(c) What will happen to the eraser if a stronger force F 1 is exerted at the same angle?
Give a reason for your answer. [2 m]
UPS 2007/2008 SF017 No. 3(a)(ii)
16.
20.0 kg
30.0 kg
table
FIGURE 4.11
A 20.0 kg box is placed on top of a 30.0 kg box as shown in FIGURE 4.11. Determine
the normal force that the table exerts on the 30.0 kg box. [3 m]
UPS 2008/2009 SF017 No. 3
17. (a) When an object is moving at a uniform velocity, does it need a force to maintain
its uniform state of motion? Justify your answer. [4 m]
(b)
FIGURE 4.12
A box of mass m is placed on an inclined plane as shown in FIGURE 4.12. Use a
free body diagram to explain why the box is at rest on the incline. [6 m]
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