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PSPM SP015
Newton’s Thrid Law of Motion
UPS 2015/2016 SF016 No. 3(b)(i)
41. State the Newton’s Third law of motion. [1 m]
UPS 2011/2012 SF016 No. 3(b)(i)
42. Based on Newton’s third law of motion, explain the pair of forces that acts when a
hockey stick hits a ball. [2 m]
UPS 2006/2007 SF017 No. 3
43.
P
30
v
Q
FIGURE 4.30
An object P of mass 4 kg is placed on an inclined plane as shown in FIGURE 4.30. It is
attached to an object Q of mass 2 kg by a string through a frictionless pulley.
(a) By using Newton’s Third Law, explain the existence of the normal force acting on
P. [2 m]
(b) When released from rest, a 9 N constant frictional force acts on P.
(i) Sketch and label two free body diagrams which show all the forces that act
on P and Q. [3 m]
(ii) Calculate the acceleration of P. [5 m]
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