Forces and Simple Machines Grade 3 Science Flashcards

Vocabulary terms and definitions based on grade 3 science concepts regarding forces, motion, simple machines, and compound machines.

Force

A push or pull that can cause an object to move, stop, or change direction.

Push

A force that moves an object away.

Pull

A force that moves an object closer.

Gravity

A force that pulls objects toward Earth.

Friction

A force that works against motion and can make objects slow down or stop.

Motion

The movement of an object.

Net Force

The sum of all forces acting on an object; if it is zero, the object will not move.

Simple Machine

A tool that helps do work more easily by changing the size or direction of a force.

Inclined Plane

A flat surface set at an angle, such as a ramp.

Lever

A bar that pivots on a fulcrum.

Pulley

A wheel with a rope around it used to change the direction of a force.

Screw

An inclined plane wrapped around a shaft or a twisted inclined plane.

Wedge

A device with a thin edge that is used to split or hold things.

Wheel and Axle

A round object that turns on a rod or axle.

Compound Machine

A machine made by combining two or more simple machines working together.

Scissors

A compound machine that combines levers and wedges.

Wheelbarrow

A compound machine that combines a wheel and axle with a lever.

Pencil Sharpener

A compound machine that combines wedges, wheel and axle, and levers.

Strength and Direction

The two characteristics that all forces always have.