Question

A ball is thrownot upward from the ground with initial speed of u.the ball is at height of 80m at two times,the interval being 6 s.find u in m/s.

Answer 1

1. Question⇒  A ball is thrownot upward from the ground with initial speed of u.the ball is at height of 80m at two times,the interval being 6 s.find u in m/s.

Explanation:

• Total time taken in travelling from 80 m instant to 80 m instant again= 2u/g
• Let, velocity at 80 m instant is V and total time taken is 6 sec, then,
• 2V/g=6
• V=30 m/s
• Now, consider motion from ground to 80m instant,
• V^2-U^2=2as.....(i)
• Putting the value of V=30 and S=80 in eqn. (i), we get
• U=50m/s