Momentum
Quantity of motion of an object.
Formula
Live Calculator
MembersVariables
Example
A 1000 kg car at 20 m/s has momentum p = 1000·20 = 20 000 kg·m/s.
How it works
Momentum tells you how hard it is to stop or change the motion of something. It depends on both how much mass the object has and how fast it is moving, so a heavy slow object and a light fast object can sometimes have the same momentum. The formula p = mv comes from combining mass, which measures inertia, with velocity, which measures motion in a particular direction.
When to use it
Use this formula whenever you need to find the motion of an object in mechanics, especially in collisions, impacts, and recoil problems. It is also useful for comparing how difficult different moving objects are to stop or redirect.
Worked example, step by step
A 2.5 kg bowling ball rolls at 8 m/s. Use p = mv Substitute the values: p = 2.5 × 8 Calculate: p = 20 Final answer: the momentum is 20 kg·m/s
Common mistakes to avoid
- Forgetting that velocity has direction, so momentum is a vector quantity
- Using speed without checking units, or mixing kg with grams and m/s with km/h
- Thinking a larger mass always means larger momentum without considering the velocity
Did You Know?
Momentum is always conserved in collisions — the principle behind rockets and Newton's cradle.
Share this formula
More in Physics
View allNewton's Second Law
BasicForce equals mass times acceleration.
Kinetic Energy
BasicEnergy of a moving object.
Gravitational Potential Energy
BasicEnergy stored due to height in a gravitational field.
Work Done
BasicWork done by a force over a distance.
Power
BasicRate of doing work.
Impulse
IntermediateChange in momentum from a force over time.