Question

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

Answer 1

The truck starts from rest, so initial velocity = 0

Distance travelled = 400 m

Time taken = 20 s

We know the equation of motion, S = ut + ½ at2

400 = 0 + ½ a * (20)2

a = 2 m/s2

Now, mass = 7 metric tonnes

= 7 * 1000

= 7000 kg

So force = mass * acceleration

F = 7000 * 2

= 14000 N

Answer 2

m = 7 tonnes

Change it in kg

= 7000 kg

s = 400 m

t = 20s

u = 0

a = ?

F = ?

Using 2nd Equation of Motion

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

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

400 = 200a

a = 2 ms^-2

Acceleration = 2 ms^-2

F = ma

F = 7000 × 2

F = 14000 N