Understanding Work, Energy and Power in Physics

Energy Concepts

Energy is a fundamental concept in physics, and several key forms are covered:

• Kinetic Energy (K.E.) is the energy possessed by an object due to its motion. K.E. = 1/2 mv²
• Gravitational Potential Energy (G.P.E.) is the energy an object possesses due to its position in a gravitational field. G.P.E. = mgh
• Elastic Potential Energy is the energy stored in deformed elastic objects like springs. E.P.E. = 1/2 kx²

The principle of conservation of energy states that energy cannot be created or destroyed, but can be transformed from one form to another.

Work and the Work-Energy Theorem

Work (W) is done when a force displaces an object over a distance. W = F ∙ d ∙ cos(θ)

The work-energy theorem relates the net work done on an object to its kinetic energy:

Wnet = ΔK.E.

Example: Lifting a Weight

A 10 kg mass is lifted 2 m vertically. Calculate the work done and change in gravitational potential energy.

Solution:

• Work done, W = F ∙ d = mg ∙ d = 10 ∙ 9.8 ∙ 2 = 196 J
• Change in G.P.E. = mg ∙ Δh = 10 ∙ 9.8 ∙ 2 = 196 J

Power and Efficiency

Power (P) is the rate of energy transfer or work done. P = W/t

Efficiency relates useful power output to total power input: Efficiency = Pout / Pin

Understanding these concepts allows solving problems using energy methods and analyzing energy transformations in mechanical systems.