Question

A man is distance 9 metre behind the door of a man when it starts moving with acceleration 2m/sto metre per second square the man is dance at full speed how far does he have to run and after what time does he get into a train what is his full speed​

Answer 1

The speed required to catch the train is u = 6 m/s.

Explanation:

Suppose, the train moves a distance ‘x’.

Therefore the distance moved by the man "S "= 9+x

• Let, u be the speed of the man with which he runs to catch the train. If ‘t’ is the time after which he catches then,

S = u x t

9+x = u x t ......(1)

• Now, the train starts from rest with an acceleration 2 m/s^2.
• Hence it travels a distance ‘x’ before the man boards it in time ‘t’.

x = 0 + ½ × 2 × t^2

x = t^2 ……….(2)

Using first equation of motion:

u = 0 + 2 × t

u = 2t …………(3)

comparing equations (1) and (3)

9+x = (2t)t

 9+x = 2t^2

 9+x = 2x  Using equation (2)

 x = 9 m

• (2)  x = t^2

 t = 3 s

• (3) => u = 2t

 u = 6 m/s

The speed required to catch the train is u = 6 m/s.

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