How to calculate force
Force is what changes an object's motion. Newton's second law says the force needed is the object's mass multiplied by the acceleration you want to give it. The heavier the object or the faster you want to speed it up, the more force it takes.
The force formula
F = m x a, where F is force in newtons, m is mass in kilograms, and a is acceleration in metres per second squared.
Worked example
To accelerate a 10 kg mass at 9.81 m/s2 (the pull of gravity) takes 10 x 9.81 = 98.1 newtons, which is simply its weight.
Frequently asked questions
What is Newton's second law?
It states that force equals mass times acceleration (F = ma). It explains how much force is needed to change an object's motion.
What is a newton?
The SI unit of force. One newton is the force that accelerates a 1 kg mass at 1 metre per second squared.
How is force related to weight?
Weight is the force of gravity on a mass: weight = mass x 9.81 m/s2. So a 10 kg mass weighs about 98.1 newtons.