A ball after falling from a height of $10\,\,m$ strikes the roof of a lift which is descending down with a velocity of $1\,\,m/s$ . The recoil velocity of the ball will be ............. $\mathrm{m}/ \mathrm{s}$
A ball after falling from a height of $10\,\,m$ strikes the roof of a lift which is descending down with a velocity of $1\,\,m/s$ . The recoil velocity of the ball will be ............. $\mathrm{m}/ \mathrm{s}$
- A
$8$
- B
$11$
- C
$12$
- D
$15$
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