Question

A ball is thrown from a height of 20 m vertically downward and has an initial velocity of v20. As the stone collides with the ground 50% of its energy is lost and bounce back to the same height. What is the initial velocity?
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Answer 1

Answer:

A ball is thrown vertically downwards from a height of 20 m with an initial velocity υ 0 . It collides with the ground, loses 50 percent of its energy ...

Step-by-step explanation:

hope it is helpful

Answer 2

Answer:

Initial energy E

i

=PE+KE=mgh+

2

1

mv

2

Energy when it reaches the ground: E=

2

1

mv

′2

since PE is zero.

Given, E=

2

1

E

i

Since it rises to the same height E

f

=mgh+0 is the final energy

⇒

2

1

(mgh+

2

1

mv

2

)=E

f

=mgh+0

v

2

=2gh=2×10×20=20

2

⇒v=20m/s