Work, Energy, Power

Work

• Force multiplied by distance

$W=Fs$

SI Unit: Joule (J)

• Scalar quantity

$1 J = 1 N m$

One joule is equal to the amount of work done when a force of 1 newtons acts for a distance of 1 metre in the direction of the force.

Energy

Ability to do work.

SI Unit: Joule (J)

Kinetic Energy

Energy a body has due to its motion.

$E_{k}=\frac12mv^2$

Potential Energy

The energy a body has due to its position in a force field.

$E_{p}=mgh$

Electromagnetic Energy

Energy transmitted from one place to another in the form of electromagnetic waves.

Waves travel at the speed of light (3×10⁸ m s^-1 in a vacuum)

Principle of Conservation of Energy

Energy cannot be created or destroyed but can only be converted from one form to another.

Power

Rate at which work is done/the rate at which energy is transferred.

SI Unit: watt (W)

• $1 W = 1 J s-1$

$Percentage⠀Efficiency=\frac{Useful⠀Output⠀Power}{Power⠀Input}\cdot100$

$Percentage⠀Efficiency=\frac{P_{o}\cdot100}{P_{i}}$