Question

A ball thrown up vertically returns to the thrower after $8\text{s}$. The velocity with which it was thrown up is -

• A. $10\text{m/s}$
• B. $20\text{m/s}$
• C. $30\text{m/s}$
• D. $40\text{m/s}$

Answer 1

The correct option is D $40\text{m/s}$

We know that,

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

$\Rightarrow 0=u\times 8+\frac{1}{2}(-10)8^2$

​​​​​​​$\Rightarrow u=40\text{m/s}$

​​​​​​​Hence, option $\left(D\right)$ is the correct answer.