Force Calculator
A force calculator determines the force acting on an object using its mass and acceleration. Force is a fundamental concept in physics and is used to describe how an object's motion changes when it is pushed, pulled, or otherwise acted upon.
Force Formula
The basic formula from Newton's Second Law is:
F = ma
where F is force in newtons (N), m is mass in kilograms (kg), and a is acceleration in meters per second squared (m/s²).
How to Calculate Force
Suppose an object has a mass of 10 kg and accelerates at 3 m/s².
Using the formula:
F = 10 × 3
F = 30 N
Therefore, the net force acting on the object is 30 newtons.
What Is a Newton?
The SI unit of force is the newton (N). One newton is the force required to accelerate a 1 kg mass at 1 m/s².
1 N = 1 kg·m/s²
Rearranging the Force Formula
If force and acceleration are known, mass can be found using:
m = F ÷ a
If force and mass are known, acceleration can be found using:
a = F ÷ m
| Known Values | Formula |
|---|---|
| Mass and acceleration | F = ma |
| Force and acceleration | m = F/a |
| Force and mass | a = F/m |
Force Due to Gravity
When calculating the gravitational force, or weight, near Earth's surface, use:
W = mg
where g is the acceleration due to gravity, approximately 9.81 m/s² near Earth's surface.
For example, the weight of a 10 kg object is approximately:
W = 10 × 9.81 = 98.1 N
Net Force
When multiple forces act on an object, the relevant quantity for Newton's Second Law is the net force. Forces acting in the same direction can be added, while forces acting in opposite directions are subtracted.
For example, if a 50 N force acts forward and a 20 N force acts backward:
Fnet = 50 − 20 = 30 N
Common Force Units
| Unit | Equivalent |
|---|---|
| Newton (N) | 1 kg·m/s² |
| Kilonewton (kN) | 1,000 N |
| Millinewton (mN) | 0.001 N |
Common Mistakes to Avoid
Make sure mass is entered in kilograms when using the SI form of F = ma. If mass is given in grams, convert it to kilograms first.
Also distinguish between mass and weight. Mass is measured in kilograms, while weight is a force measured in newtons.
Quick Summary
Force is calculated using F = ma, where mass is measured in kilograms and acceleration in meters per second squared. The resulting force is measured in newtons. When several forces act on an object, use the net force in Newton's Second Law.