MotionLab

Momentum Calculator

p = m · v, in kg·m/s.

Mass (kg)

Velocity (m/s)

Momentum (kg·m/s)

p = m · v

What you entered

Mass (kg): 5Velocity (m/s): 12

1
Momentum: p = m × v
5 × 12= 60

Result

Momentum (kg·m/s): 60

A 5kg object moving at 12 m/s carries 60 kg·m/s of momentum.

Momentum of moving objects

Momentum is mass times velocity, measured in kilogram metres per second.

Mass (kg)	Velocity (m/s)	Momentum (kg m/s)	Object
1	1	1.00	Unit case
0.145	40	5.80	Baseball at 90 mph
10	3	30.00	Bowling ball
70	5	350.00	Sprinting person
1000	20	20000.00	Car at 72 km/h
2000	15	30000.00	Van at 54 km/h

Compare the baseball with the sprinter: the person has sixty times the momentum, which is why momentum rather than speed determines how hard something is to stop. Momentum is conserved in every collision, elastic or not, which makes it more broadly useful than kinetic energy - energy is only conserved when the collision is elastic. It is also a vector, so opposite directions cancel: two identical cars meeting head-on at the same speed have zero total momentum, and both stop dead.

Mass in motion

Momentum captures how hard it is to stop a moving object — a slow-moving truck and a fast-moving bicycle can carry similar momentum, which is why both can do real damage in a collision despite very different speeds.

Conservation of momentum

In a closed system, total momentum before a collision equals total momentum after — this single principle underlies how physicists analyze everything from billiard-ball collisions to rocket propulsion.

Frequently asked questions

A 2,000 kg SUV at 15 m/s vs a 200 kg motorcycle at 40 m/s — which has more momentum?

SUV: p = 2000 × 15 = 30,000 kg·m/s. Motorcycle: p = 200 × 40 = 8,000 kg·m/s. The SUV has nearly 4× more momentum despite being slower, because its mass more than compensates for the lower speed.

How is momentum different from kinetic energy?

Momentum = mv (linear with velocity). Kinetic energy = ½mv² (quadratic with velocity). Momentum is a vector (has direction); KE is a scalar. In collisions, momentum is always conserved; kinetic energy is only conserved in perfectly elastic collisions. See the kinetic energy calculator.

What is impulse and how does it relate to momentum?

Impulse = force × time = change in momentum. A large force over a short time (hitting a wall) and a small force over a long time (airbag deployment) can produce the same impulse — but the airbag spreads the force out, reducing injury. See the impulse calculator.