Question

A body ''A' is dropped from a height h and another body 'B' is thrown horizontally with a velocity of $10{ms}^{-1}$ from the same height simultaneously. If the time taken by the body A to reach the ground is 3 s, the time taken by the body B to reach the ground is ____ s.

• A. 3
• B. 25
• C. 75
• D. 5

Answer 1

The correct option is A 3

Initial Vertical velocity of A $u_A=0$, Initial vertical velocity of B $u_B=0$

Let time $t$ to reach the ground by body B.

Using $s=ut+\frac{1}{2}a{t}^2$,

For body A, $h=0\times 3-\frac{1}{2}\times 10\times 3^2$ $\Rightarrow h=-45m$

For body B, $h=0\times t-\frac{1}{2}\times 10\times t^2$ $\Rightarrow t=3s$.