Question

A truck starts from rest and rolls down a hill with constant acceleration it travels a distance of 400m in 20s find it's acceleration. find the force acting on it if it's mass is 7tonnes


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Answer 1

u = 0m/s

v = 400 ÷ 20 = 20m/s

t = 20s

s = 400m

m = 7 ton = 700 kg

$a = \frac{v - u}{t} = \frac{20 - 0}{20} = \frac{20}{20} = 1m {/s}^{2}$

F = m × a = 700 × 1 = 700N

Answer 2

Explanation:

u = 0 (it starts from rest)

s = 400m

t = 20s

a = ?

Force = ?

2nd equation of motion

s = ut + at^2/2

400 = 0*20 + a*20*20/2

400 = 0 + a*400/2

400 = a*200

a = 2

Newton 2nd law of motion

F = ma

F = 7000*2 ( 7 tonnes = 7000 kg )

F = 14000 Answer