Question 1

What is free fall?

Accepted Answer

Free fall is motion under gravity alone with no air resistance. An object accelerates downward at g (9.81 m/s² on Earth). The kinematic equations d = ½gt² and v = gt describe distance, velocity and time.

Question 2

How fast does an object fall after a given height?

Accepted Answer

Final velocity v = √(2gh) when dropped from rest, where h is the height fallen and g is 9.81 m/s². For example, dropping from 20 m gives v = √(2 × 9.81 × 20) ≈ 19.8 m/s.

Question 3

Does this include air resistance?

Accepted Answer

No. This calculator uses the ideal vacuum model with constant gravitational acceleration. Real falling objects reach terminal velocity due to air drag, which depends on shape, mass and surface area.

Question 4

What is the value of g on other planets?

Accepted Answer

Gravity differs by body: Earth 9.81 m/s², Moon 1.62, Mars 3.71, Jupiter 24.79, Sun 274. Change the gravity field to calculate free fall anywhere in the solar system.