Chapter 5 — Exploring Forces (Grade 8)

Vocabulary flashcards covering key terms from Chapter 5: Exploring Forces (Grade 8).

Force

A push or pull on an object resulting from its interaction with another object; SI unit is the newton (N).

Push

A force applied to move an object in the direction of the force; a type of contact force.

Pull

A force that draws an object toward the source; a type of contact force.

Contact forces

Forces that require physical contact between objects to act (e.g., muscular force and friction).

Muscular force

Force produced by muscles during movement; a common example of a contact force.

Friction

The contact force that opposes motion between surfaces in contact; acts opposite to motion and depends on surface roughness.

Frictional force

Another term for friction; the resistance to motion between contacting surfaces.

Non-contact forces

Forces that act at a distance without touching, such as magnetic, electrostatic, and gravitational forces.

Magnetic force

The non-contact force exerted by magnets on magnets or magnetic materials; can attract or repel depending on poles.

Magnetic poles

North and South poles; like poles repel and unlike poles attract.

Electrostatic force

The non-contact force between charged objects; like charges repel, unlike charges attract.

Static charges

Electric charges that accumulate on surfaces due to friction and stay on surfaces until they discharge.

Static electricity

Charge buildup on surfaces due to friction, causing attraction or repulsion without contact.

Gravitational force

The non-contact force by Earth pulling objects toward itself; always attractive and acts without contact.

Weight

The gravitational force acting on an object; measured in newtons and may vary with gravity.

Mass

The amount of matter in an object; remains constant regardless of location; measured in grams or kilograms.

Upthrust (buoyant force)

The upward force exerted by a liquid on a submerged or floating object.

Archimedes’ Principle

The buoyant force on a submerged object equals the weight of the liquid displaced.

Buoyancy

The upward tendency of an object in a fluid, determined by the balance between weight and buoyant force.

Displacement (liquid)

The amount of liquid displaced by an object; related to buoyant force via Archimedes’ Principle.

Density

Mass per unit volume; affects buoyancy and whether an object sinks or floats.

Pumice

A low-density, porous rock that can float on water due to its buoyancy.

Spring balance

A device that measures weight by the extension of a spring when an object is hung from it.

Beam balance

A balance used to compare masses with known weights to determine an object's mass.

Like charges repel; unlike charges attract

In electrostatics, charges of the same kind push apart, while opposite charges pull together.

Interaction

The push or pull that occurs when two objects interact; forces arise from this interaction.

Displacement

The act of moving liquid away from an object, related to the buoyant force in Archimedes’ Principle.

Surface irregularities

Microscopic roughness on surfaces that causes friction when they are in contact.

Balanced forces

When forces on an object balance, the object remains at rest or moves with constant velocity.