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Free fall

When an object is in free fall, it is only under the influence of gravity.

That means it has no air resistance, and no other forces are acting on it.

All objects in free fall accelerate at the same rate, even if their masses are different.

The acceleration due to gravity depends on which gravitational field the object is in. On Earth, the acceleration due to gravity is about .

That’s why, if you drop a feather and a hammer in a vacuum, such as on the Moon, they will fall at the same rate and hit the ground at the same time!

The rate at which objects accelerate in free fall can be called one of two things:

  • the acceleration due to gravity - measured in
  • the gravitational field strength - measured in

Equations

Section titled “Equations”

Where:

  • is the acceleration due to gravity (or gravitational field strength) in or
  • is the distance fallen in meters ()
  • is the time taken in seconds ()