Forces, Motion, and Machines

A push or pull that is applied to an object

Force

The force that pulls objects toward the center of the Earth

gravity

Going from one place to another

Motion a bus, train, and airplane are in motion when they move from one place to another

A force that stops motion and happens between two surfaces that touch

It is easier to walk on a dry surface than it is on ice Friction It is easier to walk on a dry surface than it is on ice

A lifting or raising force

A kite depends on the wind to act as its lift.

Resistance by friction from air or water moving over a surface

drag Boats and planes are narrow. As they move, friction holds them back from moving faster.

A reaction force that pushes objects forward

Airplanes, rockets, motor boats use thrust to move

A change in speed, direction, or both

acceleration

The speed and direction of moving objects

velocity