Question

A PARTICLE STARTS from rest ,accelerates at 2 m/s2for 10 sec then goes for constant speed for 30 sec and then decelerates at 4 m/s2 till it stops. what is the distance travelled by it?

Answer 1

$$\begin{gathered} u=0 \\ a=2m/s^2 \\ t=10s \\ {s}_1=ut+0.5a{t}^2 \\ {s}_1=0+0.5\times 2\times 100=100m \\ {s}_2=v{t}_2 \\ v=u+at=0+20=20m/s \\ s2=20\times 30=600m \\ {0}^2-v^2=2(-a)s_3 \\ {s}_3=400/8=50m \\ s=s_1+s_2+s_3=100+600+50=750m \end{gathered}$$