Question

A particle starts from rest, accelerates at $2m/s^2$ for 10s and then goes for constant speed for 30s and then decelerates at $4m/s^2$ till it stops. What is the distance travelled by it

• A. 750 m
• B. 800 m
• C. 700 m
• D. 850 m

Answer 1

The correct option is A 750 m

Velocity acquired by body in 10 sec
V=0+2$\times$10=20 m/s
and distance travelled by it in 10 sec
$S_1=\frac{1}{2}\times 2\times (10{)}^2$=100m
then it moves with constant velocity (20 m/s) for 30 sec
$S_2=20\times 30$=600 m
After that due to retardation $\left(4m/s^2\right)$ it stops
$S_3=\frac{v^2}{2a}=\frac{(20{)}^2}{2\times 4}$=50m