The displacement-time graph for a particle moving in a straight line is as shown in the figure. Determine the velocity of the particle at `t=1 s, 3 s` and `6 s`. Sketch the velocity-time graph.

Explanation

`O` to `A: slope=10/2=5`
`v=5 m//s` for `t=0` to `2 s`
`A` to `C: Slope=-10/2=-5`
(The slope of a straight line is constant)
`v=-5 m//s `for `t=2` to `5 s`

`C` to `D: Slope=5/2=2.5`
`v=2.5 m//s` for `t=5` to `7 s`
`t=1 s, v=5 m//s`
`t=3 s, v=-5 m//s`
`t=6 s, v=2.5 m//s`