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06/01/2021 4:51 pm
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A truck starts from rest and rolls down a hill with a constant acceleration. It travels a distance of 400 m in 20 s. Find its acceleration. Find the force acting on it if its mass is 7 tonnes (Hint : 1 tonne = 1000 kg).
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06/01/2021 4:55 pm
u = 0 m/s
s = 400 m
t = 20 s
a = ?
F = ?
m = 7 tonnes
= 7 x 1000 kg
= 7000 kg
s = ut + \(\frac{1}{2}at^2\)
400 = (0 x 20) + \(\frac{1}{2}a(20)^2\)
= \(\frac{400 \times 2}{(20)^2}\) = a
∴ a = 2 m/s2
Force → F = ma
= 7000 x 2 = 14000 N