•Energy is the capacity to do work.
•S.I unit is Joule (J).
•Work usually means making a body or machine moves to achieve a purpose.
• To do work, energy is transferred b/w objects or converted from one form to another.
•kinetic energy is the energy due to its motion.
•Potential energy is the stored energy in a system. This form of energy is due to state, shape, and position.
•An Elastic potential energy is the energy stored in a body due to its elastic deformation.
•Gravitational potential energy is the energy stored in a body due to its height from the ground.
•The principle of conservation of energy states that energy cannot be created or destroyed, but can be converted from one form to another. The total energy in an isolated system is constant.
•As the pendulum swings, some of its energy is converted to thermal energy, due to the presence of frictional forces. This thermal energy cannot be converted back. As a result, the pendulum bob does not reach the same height. When all energy is converted to thermal energy, the. The pendulum stops swinging.
•By the principle of conservation of energy, the total energy or the total output of an ideal machine is equal to its total energy input.
•In reality the useful energy output of a machine is always less than the energy input.
•Total Energy input = useful energy output + wasted energy.
•Efficiency = useful energy output / total energy input *100
•Work done by a constant force on an object is the product of the force and the distance moved by the object in the direction of the force.
•Work done is equal to energy transformed. The S.I unit is Joule (J).
• a stationary object does not have kinetic Energy whereas a moving object does.
•A force is applied to move the stationary object. Objects get kinetic energy due to work.
E (k) = ½ mv²
E (p) = mgh
Ignoring friction for a pendulum or a free-falling body:
total energy = Gravitational P.E + Kinetic Energy
•Power is defined as the rate of work done or rate of energy conversion.
P = W / t = E / t
• SI unit of power is the watt.
• The product of the power (p) and the time taken (t) tells us the amount of work done or the amount of energy being converted.
