Question

a ball is thrown vertically upward with a velocity of 25m/s.if g is 10m/s,then calculate its height it reaches and time taken to return back.​

Answer 1

According to the question

u=25m/s displacement on hitting the ground,s = -30 m.(downward direction,so negative) s=ut 1/2at^2 acceleration due to gravity is in the downward direction. So a= -10

Answer. t=6 seconds

Answer 2

Answer:

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Given ,

Initial velocity (u) = 10m/s

Acceleration due to gravity = 10m/s²

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i) Height it reaches :-

Using ,

♦ H = u²/2g

Here ,

u = 10m/s

g = 10m/s²

H = ?

⇒ H = 10²/2(10)

⇒ H = [ 100/20 ]

⇒ H = 10/2

⇒ Height = 5m

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ii) Time taken to return back :-

Using ,

♦ v = u + gt

Here ,

v = 10m/s

u = 0m/s [since it starts from rest when it is in air for some time ]

g = 10m/s²

t = ?

⇒ 10 = 0 + 10 × t

⇒ 10 = 10t

⇒ t = 10/10

⇒ Time = 1s

Time cannot be negative

⇒ Time = 1s