Julie throws a ball to her friend Sarah. The ball leaves Julie\'s hand a distanc

Question

Julie throws a ball to her friend Sarah. The ball leaves Julie's hand a distance 1.5 meters above the ground with an initial speed of 19 m/s at an angle 46 degrees; with respect to the horizontal. Sarah catches the ball 1.5 meters above the ground.

However,After catching the ball, Sarah throws it back to Julie. The ball leaves Sarah's hand a distance 1.5 meters above the ground, and is moving with a speed of 15 m/s when it reaches a maximum height of 13 m above the ground.

Q.What is the speed of the ball when it leaves Sarah's hand?

Explanation / Answer

at maximum height , vertical component of velocity = 0

so horizontal component vx = 15 m/s

vertical displacement of ball for max. height = 13 - 1.5 = 11.5 m

Using in vertical,

vy^2 - uy^2 = 2 x ay x y

0 - uy^2 = 2 x -9.81 x 11.5

uy = 15.20 m/s

and ux = vx = 15 m/s

u = sqrt(ux^2 + uy^2) = 21.23 m/s

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