Question

A body of mass m accelerates uniformly from rest to $v_{1}$ in time $t_{1}$. As a function of time t, the instantaneous power delivered to the body is

• A. $\frac{mv_{1}t}{t_{1}}$
• B. $\frac{mv_{1}^{2}t}{t_{1}}$
• C. $\frac{mv_{1}t^{2}}{t_{1}}$
• D. $\frac{mv_{1}^{2}t}{t_{1}^{2}}$

Answer 1

Answer: (D)

$\frac{mv_{1}^{2}t}{t_{1}^{2}}$

Answer 2

$= m a \times a t$ $= m a ^ { 2 } t$ [as u = 0]

$= m \left( \frac { v _ { 1 } } { t _ { 1 } } \right) ^ { 2 } t = \frac { m v _ { 1 } ^ { 2 } t } { t _ { 1 } ^ { 2 } }$ $\left[ \operatorname { As } a = v _ { 1 } / t _ { 1 } \right]$