Page 3 - TRIAL 2

10. Situation 5: An object is at a certain height and
is influenced by gravity; which the force acting

on the object is the gravity pulling down to the
earth or ground.

W = Fs
Example :

Δh

g

W = Fs Example
= 10 x 5 = 50 J

9. Situation 4: Mass=10 kg W = Fs
An object is placed on an inclined plane; with = mgh
the force acting on it is inclined in a certain = 10×9.81×5
angle, θ to the horizontal with the 5m =490.5J
displacement.
gravity

Example 1
Read the following THREE statements and
calculate the work done:

a) A mason applies a force 500N to a wall but
W = Fs
the wall does not move
= Fx s b) A calculator 0.0201 kg falls 1m from a desk.
= Fcos ϴ x s (ignore air friction)
c) A waiter pushed a trolley of meals with
= Fs cos ϴ force 30N straight across the room 4m at

Example constant speed.

Solution
a) W = Fs
= 500 x 0 = 0 J

b) W = mgh
= 0.021 x 9.81 x 1 = 0.2 J

W = Fs c) W = Fs
o
= 10 cos 30 x 5 = 30 x 4 = 120 J
= 43.30 Joule

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