Question

Let a train is moving on straight track with uniform acceleration crosses an electric pole. If engine crosses the pole with speed 'u' and mid pt. of train with '2u', find the speed with which the tail will cross the pole?​

Answer 1

Explanation:

Let the length of the train be = L

We apply the equation of motion

2u² = u² + 2aL

2aL = 2u² - u²

The acceleration is a = 2u² - u²/ 2aL

For, half the train, the length is = L/2

and the velocity is = v

Therefore,

v² = u² + 2a . L/2

= u² + 2al

= u² + 2u² - u²/2L×L

= 2u² + 2u² - u²/ 2

= u² + 2u²/ 2 = 3u²/ 2

So, v = √3u²/ 2.