Energy and Work

Mass is a property of matter, not a form of energy.

The joule (J) is the SI unit of energy, named after James Prescott Joule.

Work is defined as the product of force and displacement in the direction of the force.

The work-energy theorem states that the net work done on an object is equal to its change in total energy (kinetic + potential).

Kinetic energy is the energy of motion and depends on the mass and velocity of the object.

Potential energy is the energy stored in an object due to its position or configuration.

The law of conservation of energy states that energy cannot be created or destroyed, only transferred or transformed from one form to another.

In a simple harmonic motion, the total mechanical energy (kinetic + potential) remains constant throughout the motion.

Work is done when a force is applied to an object and the object moves in the direction of the force.

Work done = Force × Displacement = (10 kg × 9.8 m/s²) × 5 m = 100 J.

At the highest point of its trajectory, the ball's velocity is zero, so its kinetic energy is zero.

Potential energy stored in a spring = (1/2)kx², where k is the spring constant and x is the displacement from equilibrium.

At the lowest point of its swing, the pendulum has maximum velocity and hence maximum kinetic energy.

Work done = Force × Displacement = 50 N × 0 m = 0 J.

Kinetic energy = (1/2)mv², where m is the mass and v is the velocity.