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

Options

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

Answer

A

Explanation

`A` to `B: v=0+2xx10=20 m//s`
`C` to `D: 0=v-4 t_(3)=20-4t_(3)impliest_(3)=5s`
`s_(1)=(1)/(2).2.(10)^(2)=100 m`
`s_(2)=20xx30=600m`
`s_(3)=(1)/(2).4.(5)^(2)=50 m`
Total distance`=s_(1)+s_(2)+s_(3)=750 m`
OR

Area of v-t graph`=1/2.(45+30)xx20=750 m`