Question

a truck starts from rest and Rolls down a hill with a constant acceleration it travels a distance of 400 metre in 20 second find its acceleration find the force acting on it if its mass is 7 tonnes​

Answer 1

Answer:

m = 7 tonnes

Change it in kg

= 7000 kg

s = 400 m

t = 20s

u = 0

a = ?

F = ?

Using 2nd Equation of Motion

{simplies s = ut + \dfrac{1}{2}at^{2}}

{simplies 400 = 0 + \dfrac{1}{2}\times a\times (20^{2})}

400 = 200a

a = 2 ms^-2

Acceleration = 2 ms^-2

F = ma

F = 7000 × 2

F = 14000 N

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Answer 2

Answer:

$7000 \ N$

Explanation:

The truck was at rest initially, therefore,

$v_0 = 0 \ ms^{-1}$

It covers 400 metres in 20 seconds, therefore,

$v = \frac{400 \ m}{20 \ s} = 20 \ ms^{-1}$

So, the acceleration is,

$a = \frac{ ( 20 - 0 ) ms^{-1} }{20 \ s } = 1 \ ms^{-2}$

We now have the acceleration. Mass is given which is 7 tons, which is 7000 kg.

So, the force is,

$F = ma = 7000 \times 1 = 7000 \ N$