Gravity and free fall

In short: Gravity pulls all bodies towards the Earth. Without air resistance all objects fall at the same speed, with an acceleration of about 9.81 m/s².

In more detail: After one second a falling body is about 9.8 m/s fast, after two seconds about 19.6 m/s. The distance fallen grows with the square of time.

In detail

• Distance fallen: s = ½ · g · t². After 3 seconds about 44 metres.
• Air resistance: A feather falls slowly because air slows it. In a vacuum feather and stone fall equally fast.
• Terminal velocity: Skydivers reach about 200 km/h when air resistance and weight balance.
• Weight and mass: Mass stays the same everywhere, weight is the force. On the Moon you weigh about a sixth.
• Weightlessness: Astronauts in orbit are constantly falling but miss the Earth (reibung-im-alltag).