Question

A body is projected vertically upward with an initial velocity u. if acceleration due to gravity is g,the time for which it remains in air ,is

Answer 1

The ball is thrown upwards withvelocity 19.6 m/s. During theupward motion it experiences -9.8 m/s² acceleration due to which it comes to rest momentarily at the highest point in air. We can calculate the time taken to reach the heighest point. So the ballreaches the topmost point in air in 2 seconds.

Answer 2

Hey !

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Use the method as shown in the link. It will help you to find the maximium height reached by the ball.

Once, you calculated height (s) reached by the object. You can find the time taken by the ball to attain maximum height using Newton's IInd law of motion which is given by :

s = u t + 1/2 a t2 ........(1)

As u = 100 m/s

a = -10 m/s2

Plug in values of a, u, and s (maximum height attained by the ball) in eq. 1, you can calculate time (t) taken by the ball to attain the maximium height.

c) Velocity after 5s can be calculated by using formula, v = u + at

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Thanks !