Question

A ball is thrown vertically upwards. It returns 6seconds later. The greatest height reached by ball is _______ (taken g = 10ms–2) 1) 90m 2) 70m 3) 20m 4) 45m​

Answer 1

Explanation:

A ball is thrown vertically upwards and it returns 6 second later.

So time of flight = 6s time it took to reach maximum height =

6/2 = 3s

acceleration = -10 m/s^2 (downward is negative)

let initial velocity= u final velocity at top, v = 0

we know that v = u + at

=> 0u - 10×3

=> 0 = u - 30

=> u = 30 m/s

Vol 84

Let the highest point reached = h meter

hu^2/2g = 30^2 / (2×10) = 45 meter

Greatest height reached = 45m initial velocity= = 30 m/s