Question

The acceleration-time graph of a body is shown below. If initial velocity of body is $20\text{m/s}$, then velocity of body after $10\text{s}$ is

• A. $20{\text{ms}}^{-1}$
• B. $40{\text{ms}}^{-1}$
• C. $50{\text{ms}}^{-1}$
• D. $70{\text{ms}}^{-1}$

Answer 1

The correct option is D $70{\text{ms}}^{-1}$

The area under the acceleration-time graph gives the change in velocity in that time interval. Therefore in $10\text{s}$, the change in velocity is $=5\times 10=50{\text{ms}}^{–1}$. Since the initial velocity is $20{\text{ms}}^{-1}$ and acceleration is positive the final velocity would therefore be $50+20=70{\text{ms}}^{–1}$