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$2m/s^2$ 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

$v=0+2\times 10=20m/s$

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

$S_2=20\times 30=600m$

After that due to retardation $\left(4m/s^2\right)$ it stops

$S_3=\frac{v^2}{2a}=\frac{(20{)}^2}{2\times 4}=50m$
So total distance travelled is 750 m.