Question

A particle starts from rest at $t=0$ and moves in a straight line with acceleration as shown in the following figure.

The velocity of the particle at $t=3$ seconds is

• A. $2\text{m/s}$
• B. $4\text{m/s}$
• C. $6\text{m/s}$
• D. $8\text{m/s}$

Answer 1

The correct option is B $4\text{m/s}$

As object starts from rest, area of $a-t$ curve gives change in velocity
Velocity at 3 seconds = total algebraic sum of area under the curve.
or $v=4\times 2-4\times 1$
$=8-4=4\text{m/s}$
Hence, the correct answer is option (b).