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 9.81ms^{-2}.

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:

Equations

\text{acceleration due to gravity} = \frac{2 \times \text{distance fallen}}{\text{time taken}^2}

g = \frac{2h}{t^2}

Where:

flashcards

QuestionAnswer
What is the definition of free fall?An object is in free fall when it is only under the influence of gravity, with no air resistance or other forces acting on it.
What is the acceleration due to gravity on Earth?Approximately 9.81ms^{-2}.
What are the two names for the rate at which objects accelerate in free fall?Acceleration due to gravity (measured in ms^{-2}) and gravitational field strength (measured in Nkg^{-1}).
What is the equation for acceleration due to gravity in terms of distance fallen and time?g = \frac{2h}{t^2}
In the equation g = \frac{2h}{t^2}, what does h represent?h is the distance fallen in meters (m).
In the equation g = \frac{2h}{t^2}, what does t represent?t is the time taken in seconds (s).
Why do a feather and a hammer hit the ground at the same time on the Moon?All objects in free fall accelerate at the same rate, and on the Moon there is no air resistance (vacuum), so they fall at the same rate.
What determines the acceleration of an object in free fall?The gravitational field the object is in.