Question

A ball is dropped onto a horizontal floor. It reaches a height of $144cm$ on the first bounce and $81cm$ on the second bounce, the height it attains on the third bounce is

• A. $45.6cm$
• B. $81cm$
• C. $144cm$
• D. $0cm$

Answer 1

The correct option is A $45.6cm$

$e=\sqrt{\frac{h_2}{h_1}}$

$\Rightarrow e=\sqrt{\frac{81}{144}}=.75$

$e=0.75$

which will be same for all further collision i.e.,

$e=\sqrt{\frac{h_3}{h_2}}$

so $h_3=\frac{81}{144}\times 81=45.6cm.$