Question

The engine of a locomotive exerts a constant force of 6.8 105 N to accelerate a train to 80 km/h. Determine the time (in min) taken for the train of mass 1.1 107 kg to reach this speed from rest.

Answer 1

Answer:

t = 6 minutes

Explanation:

Given that,

Force,$F=6.8\times 10^5\ N$

Initial speed of the train, u = 0

Final speed of the train, v = 80 km/h = 22.22 m/s

The mass of the train, $m=1.1\times 10^7\ kg$

We need to find the time taken by the train to come to rest. We know that,

F = ma

$F=\dfrac{m(v-u)}{t}\\\\t=\dfrac{m(v-u)}{F}\\\\t=\dfrac{1.1\times10^7\times (22.22-0)}{6.8\times 10^5}\\\\t=359.44\ s$

or

t = 6 minutes (approx)

So, the required time is equal to 6 minutes.