Staying on course
Once something is on the move, it will keep moving a straight line. This is why passengers are thrown forwards when a car brakes. It is also why water stays in a bucket if you whirl it around in a circle, while the bucket turn a corner, the water tries to continue straight on.

Strapped in
Seat belts bring people to a safe halt if a car stops suddenly.

How to lose weight
Because the Earth is not exactly round, the force of gravity varies slightly fro place to place. If you weight 30 kg (66 lb) at the North Pole, you would find that you weighed only 29.85 kg (65.8 lb) at the Equator.