Question

The acceleration a of moving body from rest is 2 (t - 1). Then, the velocity at 5 s will be

• A. 15 m/s
• B. 25 m/s
• C. 35 m/s
• D. 45 m/s

Answer 1

Answer: (A)

15 m/s

Answer 2

Acceleration $a=\frac{dv}{dt}=2(t-1)$ Integrating, $v={{t}^{2}}-2t+c$ Velocity $v=0$ at $t=0$ $\therefore$ $c=0$ $v={{t}^{2}}-2t$ $\therefore$ Velocity at 5 s $v={{(5)}^{2}}-2\times 5$ $=15m/s$