Physics Homework Help?

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Cmoney

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I will put best answer as the first person to put up the correct answers for the following two questions. Thank You.

A baseball is hit nearly straight up into the air with a speed of 17 m/s. ?

1. How high does it go? (In meters)
2. How long is it in the air? (In seconds)
 
<< How high does it go? (In meters) >>

Working formula is

Vf^2 - Vo^2 = 2gs

where

Vf = final velocity = 0 (when ball is at its maximum height)
Vo = initial velocity = 17 m/sec (given)
g = acceleration due to gravity = 9.8 m/sec^2 (constant)
s = maximum height attained by ball

Substituting appropriate values,

0 - 17^2 = 2(-9.8)(s)

NOTE the negative sign attached to the acceleration due to gravity. It simply denotes that the ball is slowing down as it is going up.

Solving for "s"

s = 14.7 meters


<< How long is it in the air? >>

Working formula is

Vf - Vo = gT

where

T = time for ball to reach its maximum height3

and all the other terms have been previously defined.

Substituting values,

0 - 17 = (-9.8)T

and solving for "T"

T = 1.73 sec.

Therefore, total flight time = 2T = 3.46 sec.

Hope this helps.
 
Initial speed u = 17 m/s

1. u^2/(2g) = 17^2/(2 * 9.8) = 289/19.6 = 14.7 m

2.) 2u/g = 2 * 17/9.8 = 3.47 second

Note: After time u/g, it reaches to maximum height. It takes u/g to fall from maximum height to the point of throw. Therefore, in total it is in the air for 2u/g time.
 
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