A bus starts from rest and rolls down a hill with a constant acceleration. The weight of the bus is 6.8 tonnes and it has luggage of 200 kg tied with a rope on its top. The weight of the driver and the rope is negligible.
(i) If it travels a distance of $400 m$ in $20 s$ . Find its acceleration and also the force acting on it.

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Solution

Given:

Initial velocity, $u = 0 m s^{- 1}$

Distance covered, $s = 400 m$

Time taken, $t = 20 s$

Total mass, $m = 6800 + 200 = 7000 k g$

From the second equation of motion:
$s = u t + \frac{1}{2}$ at $^{2}$ [0.5 Marks]

$400 = 0 (20) + (a) (400)$ [0.5 Marks]

$a = 2 m s^{- 2}$ [0.5 Marks]

Force $= m (a)$ [0.5 Marks]

Force $= 7000 (2) N$ [0.5 Marks]

Force $= 14, 000 N$ [0.5 Marks]

Therefore, a force of $14, 000 N$ is acting on the bus.

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A bus starts from rest and rolls down a hill with a constant acceleration. The weight of the bus is 6.8 tonnes and it has luggage of 200 kg tied with a rope on its top. The weight of the driver and the rope is negligible.
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