The velovity-time graph of a particle moving in a straitht line is shown in . The acceleration of the particle at `t=9 s` is.
.

Options

A. Zero
B. `5 m s^(-2)`
C. `-5 m s^(-2)`
D. `-2 m s^(2)`

Answer

C

Explanation

Acceleration between `8` and `10 s or at `t=9 s`:
`a= (v_(2)-v_(1))/(t_(2) -t_(1)) =(5-15)/(10-8) =- ms^(-2)`.