A particle is projected upwards with velocity `40 m//s.` Taking the value of `g=10 m//s^2` and upward direction as positive, plot a-t,v-t and s-t graphs of the particle from the starting point till it further strikes the ground.

Answer

A

Explanation

Upward journey time = downward journey time= `u/g=40/10=4s`
`:.` Total time of journey = `8s`
Maximum height attained by the particle `= u^2/(2g)=(40)^2/2xx10=80 m`
a-t graph During complete journey `a=g=-10 m//s^2`
Corresponding a-t graph is as shown below.

v-t graph In upward journey velocity first decrease from `+40 m//s` to `0`. Then, in downward
journey it increases from `0` to `-40 m//s`. Negative sign just signifies its downward direction.
Corresponding v-t graph is as shown below.

s-t graph In upward journey displacement first increases from `0` to `+80 m.` Then, it decreases from `+80 m` to `0`. Corresponding s-t graph is as shown below.