Keywords: force and extension.

Keywords: galaxies, red shift, the universe.

Keywords: lenses, convex lenses and magnification.

Keywords: magnetic fields, electromagnets, motors.

Keywords: refraction.

Keywords: transformers.

Keywords: experimental results, converting units, error and uncertainty.

Keywords: scalars and vectors, velocity and acceleration.

Keywords: reaction times, breaking distance, stopping distance.

Keywords: atmospheric pressure, resultant forces.

Keywords: transverse and longitudinal waves, loudspeakers.

Keywords: the motor effect, magnetic flux density.