# physics

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from what height must a heavy elastic ball be dropped on a floor ,so thatafter reboundingthrice it will reach a height of 16 m?take e=(0.5)

• physics -

After the 1st rebounce the speed is v/2, after the 2nd rebounce – v/4,
after the third rebounce –v/8, =>
m(v/8)²/2=mgh₁
v=sqrt(128gh₁) =141.7 m/s
mv²/2=mgh
h= v²/2g=141.7²/2•9.8=1024 m

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