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 7 tonnes. ( 1 tonne = 1000kg)

Answer 1

Given:
u = 0 m/s
s = 400 m
T = 20 s
s=uT+1/2 aT²
400 = 0 * 20 + 1/2 * a * 20 * 20
400 = 0 + 200a
200a = 400
a = 400/200
a = 2 m/s²

Force = Mass * acceleration
f = 7 * 1000 * 2
f = 14000 N

∴ acceleration of the truck is 2 m/s² and the force of the truck is 14000 Newton.

Answer 2

u=0m/s ( starts from rest )
time=20s
distance=400m
Acc to 2nd equation of motion
s=ut+1/2at^2
400=0x20+1/2xax20x20
400=0+1/2x400a
400=0+200a
400=200a
a=400/200
a=2m/s^2

Mass=7 tonnes
So, mass= 7000kg ( 1 tonne= 1000kg)

Now acc to Newton's 2nd law of motion
Force= Mass x Acceleration
Now, Force= (7000x2) Newton
Therefore, Force= 14000 Newton

THANKS!