Chapter 3 - "Work , Energy and Simple Machines"

Use derivations

What is work in physics?

Work is said to be done when a force acting on an object causes displacement in the direction of the force.

What is the formula for work done?

W = F × s, where W = work done, F = force, and s = displacement.

What is the SI unit of work?

Joule (J).

What is 1 joule of work?

1 joule is the work done when a force of 1 newton causes a displacement of 1 metre in the direction of the force. 1 J = 1 N × 1 m.

What is the SI unit of force?

Newton (N).

What is the SI unit of displacement?

Metre (m).

What does the area under a force-displacement graph represent?

The area under a force-displacement graph gives the work done.

Is work a scalar or vector quantity?

Work is a scalar quantity because it has magnitude but no direction.

When is work done zero?

Work is zero in three important situations: 1. When there is no displacement. 2. When there is no force acting on the object. 3. When the force is perpendicular to the displacement.

Give an example where work is zero because there is no displacement.

Pushing a wall that does not move. Force is applied, but displacement is zero, so work done is zero.

Give an example where work is zero because force is perpendicular to displacement.

When an object moves horizontally while the force of gravity acts vertically downward. The force and displacement are perpendicular, so work done by gravity is zero.

What is energy?

Energy is the capacity of an object to do work.

What is the SI unit of energy?

Joule (J).

What are the main types of mechanical energy?

Kinetic energy and potential energy.

What is mechanical energy?

Mechanical energy is the energy possessed by an object due to its motion or position. It is the sum of kinetic energy and potential energy.

What is kinetic energy?

Kinetic energy is the energy possessed by an object due to its motion.

What is the formula for kinetic energy?

K = 1/2 mv², where m = mass and v = velocity.

What is the SI unit of kinetic energy?

Joule (J).

What is potential energy?

Potential energy is the energy possessed by an object due to its position or configuration.

What is gravitational potential energy?

Gravitational potential energy is the energy possessed by an object because of its height above the ground or a chosen reference level.

What is the formula for gravitational potential energy?

U = mgh, where m = mass, g = acceleration due to gravity, and h = height.

What is the SI unit of potential energy?

Joule (J).

What is the SI unit of mass?

Kilogram (kg).

What is the SI unit of velocity?

Metre per second (m/s).

What is the SI unit of acceleration?

Metre per second squared (m/s²).

What is the SI unit of height?

Metre (m).

What is the SI unit of acceleration