A boy reaches out of a window and tosses a ball straight up with a speed of 11 m

Question

A boy reaches out of a window and tosses a ball straight up with a speed of 11 m/s. The ball is 21 m above the ground as he releases it. Use energy to find the ball's maximum height above the ground. Express your answer to two significant figures and include the appropriate unrts. Use energy to find the ball's speed as it passes the window on its way down. Express your answer to two significant figures and include the appropriate units. Use energy to find the speed of impact on the ground. Express your answer to two significant figures and include the appropriate units.

Explanation / Answer

at max height ball speed = 0

(KE +UE )i = (KE +UE )f

1/2*m*11^2 + m*g*21 = 0 + m*g*Hmax

0.5*121 + 9.8*21 = 9.8*Hmax

Hmax = 27.1735 m .............answer

part 2 )

by energy conservation

(KE +UE )i = (KE +UE )f

1/2*m*11^2 + m*h*21 = 1/2*m*v^2 + m*g*21 ...............(at same height )

so

V= 11 m/s same speed by it was thrown upward

Part 3

(KE +UE )i = (KE +UE )f

windows = ground

1/2*m*11^2 + m*g*21 = 1/2*m*v^2 + 0

0.5*121 + 9.8*21 = 0.5*v^2

v = 23.0781 m/s

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