Deck 1 — Forces & Friction

Force

A push or pull resulting from the interaction between two objects.

Forces

Forces only exist when objects interact.

Effects of a Force

Can change motion, change shape or size, cause turning, and apply pressure.

SI Unit of Force

newton (N).

Instrument for Measuring Force

Newton meter or spring balance.

Contact Forces

Forces that require objects to touch.

Normal Force

A contact force exerted by a surface on an object.

Tension

A contact force transmitted through a rope, string or cable.

Friction

A contact force that opposes motion between two surfaces in contact.

Upthrust (Buoyant Force)

An upward contact force exerted by a fluid on an object.

Thrust

A contact force that pushes an object forward.

Air Resistance (Drag)

A contact force that opposes motion through air.

Non-contact Forces

Forces that act without physical contact.

Gravitational Force (Weight)

A non-contact force caused by gravity.

Magnetic Force

A non-contact force between magnets or magnetic materials.

Electrostatic Force

A non-contact force between electrically charged objects.

Friction

A force that opposes motion between two surfaces in contact.

Factors Affecting Friction

Surface roughness, type of surfaces and the normal force.

What Friction Does NOT Depend On

Surface area.

Positive Effects of Friction

Walking, holding chopsticks, braking and writing.

Negative Effects of Friction

Increases fuel consumption, causes wear and tear, and produces unwanted heat.