A truck starts from rest and rolls down a hill with a constant acceleration. It travels a distance of 400m in 20s. Find the acceleration. Find the force acting on it if its mass is 7 tonnes. (Hint: 1 tonne = 1000 kg.)

Given data:Mass of stone(m)=7000 kg
Distance(S)=400 meter
Time(t)=20 second

1. We have to find the acceleration of the truck
   So from the equation of motion
   S=ut+1/2at², where
   u=0
   S=1/2at²
   a=2S/t²=2×400/20×20=2msec²
2. Force acting on truck
   So,from newton's 2nd law of motion
   →F=ma=7000×2=14000N=14kN