Question

Hi brainly users....answer this .....

Answer 1

According to your question, I have solved in three cases respectively :-

In first case, When ball throws upward direction from boy's level.

=> v=u+(-g)t
Here (g) is -ve because ball is going upward.
=> 0 = 15+(-10)t
=> -15 = -10t
=> 15 = 10t
=> t = 15/10 s
=> t = 1.5 s

Height from the boy's level to upward direction.

=> h=ut-1/2gt^2
=> h= (15x1.5)-1/2 x 10 x 1.5 x 1.5
=> h= 22.5 - 11.25
=> h= 11.25 m

In second case, When the ball coming back.

=> h= ut+1/2gt^2
=> 11.25= 0+ 1/2 x 10 x t^2
=> 11.25= 5t^2
=> t^2 = 11.25/5
=> t^2 = 2.25
=> t = 1.5 s

In third case, When ball falling from boy's level to ground.

=> h=ut+1/2gt^2
=> 50+11.25= 0+1/2 x 10 x t^2
=> 61.25= 5t^2
=> t^2= 61.25/5
=> t^2= 12.25
=> t= 3.5 s

So, from boy's level to ground level time taken = 3.5 s

In these all, When ball falling from upward direction to ground level = (1.5+3.5) s = 5 s.

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