Force and Time Method
J = F × Δt
Use this method when you know the average force and the duration for which that force acts.
Impulse Calculator
Calculate impulse from force and time or determine momentum change using mass, initial velocity, and final velocity.
Calculate Impulse
Select a calculation method and enter the known values.
What Is an Impulse Calculator?
An impulse calculator determines the effect of a force acting on an object over a period of time. In physics, impulse is equal to the change in an object’s linear momentum.
You can calculate impulse directly by multiplying average force by contact time. You can also calculate it by multiplying mass by the change between final and initial velocity.
Momentum Change Method
J = m(vf − vi)
Use this method when you know the object’s mass, initial velocity, and final velocity.
One newton-second is equivalent to one kilogram-meter per
second. Therefore, impulse and change in momentum have equal
numerical values in SI units.
How the Impulse Calculator Works
This tool converts all entered measurements into standard SI units before performing the calculation. This helps provide consistent results when you use kilonewtons, milliseconds, grams, or kilometers per hour.
1
Select a Method
Choose force and time or choose momentum change.
2
Enter Your Values
Add the known force, time, mass, or velocity values.
3
Choose Units
Select the measurement unit associated with every value.
4
View the Result
Get impulse, momentum change, direction, and detailed steps.
Impulse Formula and Variables
Impulse is represented by the symbol J. It is a vector quantity, meaning it has both magnitude and direction.
| Symbol | Meaning | Standard Unit |
|---|---|---|
| J | Impulse | Newton-second, N·s |
| F | Average applied force | Newton, N |
| Δt | Force application time | Second, s |
| m | Object mass | Kilogram, kg |
| vi | Initial velocity | Meter per second, m/s |
| vf | Final velocity | Meter per second, m/s |
| Δp | Change in momentum | Kilogram-meter per second, kg·m/s |
Impulse From Force and Time
Suppose an average force of 250 N acts on an object for 0.4 seconds. The impulse is:
J = 250 × 0.4 = 100 N·s
Impulse From Momentum Change
Suppose a 5 kg object changes velocity from 2 m/s to 12 m/s. The velocity change is 10 m/s:
J = 5 × (12 − 2) = 50 N·s
Where Impulse Is Used
Impulse calculations are useful in mechanics, sports science, vehicle safety, engineering, and collision analysis.
Vehicle Safety
Airbags and crumple zones increase the time over which a person’s momentum changes. Increasing this time can reduce the average force experienced during a collision.
Sports
Athletes use follow-through to increase the time during which force acts on a ball. This can produce a greater change in momentum.
Engineering and Testing
Engineers study impulse when analyzing impacts, machine components, protective materials, and structures exposed to sudden forces.
Frequently Asked Questions
Impulse is the product of average force and the time interval during which the force acts. It is also equal to the change in momentum.
The SI unit of impulse is the newton-second, written as N·s. It is equivalent to kg·m/s.
Impulse is not the same as an object’s total momentum. Impulse is equal to the change in momentum caused by a force.
Yes. A negative impulse means the change in momentum is opposite to the direction defined as positive.
Divide impulse by the contact time. The rearranged formula is F = J ÷ Δt.
For the same momentum change, increasing contact time reduces the required average force. This principle is used in airbags, helmets, and protective padding.
The impulse-momentum theorem states that the net impulse acting on an object equals its change in linear momentum.