The acceleration versus time graph for a particle moving along a straight line is shown in the figure. If the particle starts from rest at t = 0, then its speed at t = 30 sec will be :

Options

A. `20m//sec`
B. `40m//sec`
C. `0m//sec`
D. `-40m//sec`

Answer

B

Explanation

The acceleration ……..
For a - t curve
speed = |velocity|
speed (at t = 30 sec) `= |10xx4-4xx20|`
`= |40-80| = |-40| = 40m//sec`.