Question

Two bodies, A (of mass 1 kg) and B (of mass 3 kg) are dropped from heights of 16 m and 25 m, respectively. The ratio of the time taken by them to reach the ground is

• A. $\frac 54$
• B. $\frac 85$
• C. $\frac 58$
• D. $\frac 45$

Answer 1

Answer: (D)

$\frac 45$

Answer 2

We know from equation of motion that when a body is dropped

$t =\sqrt {\frac {2h}{g}}$

$\frac {t_A }{ t_B }= \frac {(\sqrt {\frac {2h_A}{g}})}{(\sqrt {\frac {2h_B}{g}})}$

$\frac {h_A}{h_B }= \sqrt {\frac {16}{25 }}$

$\frac {h_A}{h_B }$ $=\frac 45$

So, the correct option is (D): $\frac 45$