Question

The displacement of a body in $8s$ starting from rest with an acceleration of $20{\text{cm/s}}^2$ is

• A. $64\text{m}$
• B. $64\text{cm}$
• C. $640\text{cm}$
• D. $0.064\text{m}$

Answer 1

The correct option is C $640\text{cm}$

Given acceleration = $20{\text{cm/s}}^2=0.20{\text{m/s}}^2$

Using second equation of motion, we know
$S=ut+\frac{1}{2}a{t}^2$
At $t=0$, body is at rest
$\therefore u=0$
$\Rightarrow S=\frac{1}{2}a{t}^2=\frac{1}{2}\times \left(0.2\right)\left(64\right)$
$=6.4\text{m}=640\text{cm}$