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

Given, distance covered by the truck (s) = 400 meters

Time taken to cover the distance (t) = 20 seconds

Initial velocity of the truck (u) = 0
{since it starts from rest}

We know that, $$s = ut + \frac{1}{2} at^2$$

$$\therefore$$ $$400 = 0 × 20 + \frac{1}{2} (a)(400) \ = \ 2 m/s^2$$

Now, force = mass × acceleration

$$\therefore$$ force acting on truck = 7000 × 2 = 14000 N