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Power is considered one of the most asked concept.
29 Questions around this concept.
A body of mass m accelerates uniformly from rest to V in time T The instantaneous power delivered to the body as a function of time is given by :
A body of mass m accelerates uniformly from rest to in time The instantaneous power delivered to the body as a function of time t is :
A body is moved along a straight line by a machine delivering constant power. The distance moved by the body in time t is proportional to:
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Initially block of mass 2 kg was at rest. If variable force $F=(2 t-4) N$ acts on a block. Then find the average power delivered to the block for time interval $t=0 \mathrm{~s}$ to $\mathrm{t}=1 \mathrm{sec}$.
A weight lifter lifts 300 kg from the ground to a height of 4m in 3 seconds. The average power generated by him is
A body is moved along a straight line by a machine delivering constant power. The distance moved by the body in time t is proportional to
Definition-
Power is defined as the rate at which work is done or energy is transferred.
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
$$
d t \rightarrow \text { interval of time }
$$
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