P2a Forces in Action

Density

The mass of an object divided by its volume.

Pressure

The force acting per unit area.

Energy

The capacity to do work, calculated as mass times specific heat capacity times the temperature change or as mass times specific latent heat.

Force exerted by a spring

The product of the spring constant and the extension of the spring.

Weight

The force of gravity acting on an object, calculated as mass times gravitational field strength.

Friction

A contact force that opposes the motion of an object sliding over a rough surface.

Normal contact force

The force exerted by a solid surface perpendicular to the object resting on it.

Push

A force that acts to move an object away from something.

Upthrust

The upward force on an object in a fluid due to differences in pressure.

Magnetism

A non-contact force experienced by a magnetic object in a magnetic field.

Gravitational Force (weight)

The force acting on a mass due to a gravitational field.

Electrostatic

A non-contact force acting on a charged object in an electric field.

Newton’s First Law of Motion

An object remains at rest or moves at a constant speed unless acted upon by a resultant force.

Hooke’s Law

The extension of a spring is directly proportional to the force applied to it.

The Principle of Moments

For an object to be in balance, the sum of clockwise moments must equal the sum of anticlockwise moments about a pivot.

Archimedes Principle

The upthrust on a body immersed in fluid is equal to the weight of the fluid displaced.

Effort

The force applied to move or lift an object.

Elastic deformation

A temporary change in shape or length, allowing the material to return to original shape when the force is removed.

Free Body Diagram

A diagram showing all forces acting on an object.

Fulcrum

The pivot point of a lever.

Gear

Wheels with toothed edges that rotate on an axle, transferring motion between gears.

Lever

A rigid object that pivots around a fulcrum to amplify force.

Linear

A graph representing a straight-line relationship between two variables.

Load

The object or force that is being moved by a lever or system.

Moment

The turning effect produced by a force around a pivot.

Plastic deformation

A permanent change in shape where the material remains altered after the force is removed.

Spring Constant

A measure of the stiffness of a spring, defined as force per unit extension.