Power - Practice Questions & MCQ

1. Definition-

Power is defined as the rate at which work is done or energy is transferred.

2. Dimension -

$M L^2 T^{-3}$
3. Units-
- SI- Watt or Joule/sec
- CGS- Erg/sec
4. Average power-

$$
P_{a v}=\frac{\Delta w}{\Delta t}=\frac{\int_0^t p \cdot d t}{\int_0^t d t}
$$

5. Instantaneous power-

$$
P=\frac{d w}{d t}=P=\vec{F} \cdot \vec{v}
$$

Where, $\vec{F} \rightarrow$ force

$$
\vec{v} \rightarrow \text { velocity }
$$

i.e. power is equal to the scalar product of force with velocity
6. Power expressed as the rate of change of kinetic Energy

$$
P=\frac{d k}{d t}
$$

Where, $d k \rightarrow$ change in kinetic energy

$$
d t \rightarrow \text { interval of time }
$$