🎯 Knowledge Check
Physics — WORK AND ENERGY
Frequently Asked Questions
Work is done when a force causes displacement of an object in the direction of the force.
Work done \((W) = Force (F) × Displacement (s) × cos\,\theta\), where \(\theta\) is the angle between force and direction of displacement.
The SI unit of work is joule (J).
A force must act on the object and the object must move in the direction of the force.
Energy is the capacity to do work or cause change.
The main forms are kinetic energy and potential energy; other forms include mechanical, chemical, electrical, heat, and nuclear energy.
Kinetic energy is the energy possessed by a body due to its motion.
Kinetic Energy \((KE) =\frac{1}{2} \times (\text{mass } m)\times (\text{velocity } v)^2\)
Potential energy is the stored energy an object has due to its position or configuration.
Gravitational Potential Energy (PE) = mass (m) × gravity (g) × height (h)
Mechanical energy is the sum of kinetic and potential energy in a system.
A moving car has kinetic energy.
Water at the top of a dam possesses potential energy.
Energy can neither be created nor destroyed; it only changes form. The total energy in a closed system remains constant.
In a pendulum, energy continuously converts between kinetic and potential, but total energy stays the same.