Power

Power

Definition and Measurement

• Power is the rate of doing work or the amount of energy transferred per unit time. It is a scalar quantity.
• It is measured in Watts (W), which is equivalent to one joule of work per second (J/s).

Calculation

• Power can be calculated using the formula, P = W/t, where P is power, W is work done and t is time taken. This formula is applicable when the work done is constant over time.
• When force and velocity are involved, power can also be calculated using the formula P = Fv cos θ, where F is the force applied, v is the velocity of the object, and θ is the angle between the force and the direction of motion.

Applications

• The concept of power is extensively used in the fields of mechanics and electricity.
• Power has both instantaneous and average forms. The average power is the total work done divided by the total time, while the instantaneous power is the power at a specific moment.

Higher Power and Efficiency

• Higher power means that work is done at a faster rate. For example, a more powerful car can reach a certain speed in less time than a less powerful one.
• In the context of mechanical systems, efficiency is the ratio of useful power output to the total power input. This can be calculated using the formula: Efficiency = (Useful Power Output / Total Power Input) x 100%.