A man throws a ball vertically upward and it rises through $20 m$ and returns to his hands. What was the initial velocity $(u)$ of the ball and for how much time $(T)$ it remained in the air?

u = 10 m/s, T = 2 s

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u = 10 m/s, T = 4 s

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u = 20 m/s, T = 2 s

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u = 20 m/s, T = 4 s

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Solution

The correct option is D $u = 20 m/s, T = 4 s$
From third equation of motion $v^{2} - u^{2} = 2 a S$
In this case, the acceleration acts downward due to gravity, then
$0 - u^{2} = - 2 g h$
$u^{2} = 2 \times 10 \times 20$
$u = 20 m/s$
From first equation of motion
$0 = 20 - g t$
$t = \frac{20}{10} = 2 s$
Now, $T$ = 2*t = 4s
Therefore, option d is correct.

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A man throws a ball vertically upward and it rises through 20 m and returns to his hands. What was the initial velocity (u) of the ball and for how much time (T) it remained in the air?

The correct option is D u=20 m/s,T=4 sFrom third equation of motion v2–u2=2aS In this case, the acceleration acts downward due to gravity, then 0–u2=–2gh u2=2×10×20 u=20m/s From first equation of motion 0=20–gt t=2010=2s Now, T = 2*t = 4s Therefore, option d is correct.

A man throws a ball vertically upward and it rises through $20 m$ and returns to his hands. What was the initial velocity $(u)$ of the ball and for how much time $(T)$ it remained in the air?