F = ma

Lesson 3 of 11 · 7 min · Free, no account needed

What you will learn

Newton's second law: net force = mass × acceleration, F = ma.
Turned around, a = F ÷ m: double the force, double the acceleration; double the mass, half the acceleration.
Mass is how hard a thing is to speed up. 1 N gives 1 kg an acceleration of 1 m/s², so 1 N = 1 kg·m/s².

Why does an empty trolley jump forward, while a full one barely moves?
Same push on both. Guess how fast the full one speeds up.
Pull a 2 kg cart with different forces. Push after each change.
Each run plots one point: force across, acceleration up.
Now keep the force at 12 N and load the cart with masses.
The empty cart is 1 kg. Each change runs it again.
Force, mass and acceleration in one law.
Newton's second law: F = m × a. The net force equals the mass times the acceleration.
Mass (kg) measures how hard a thing is to speed up or slow down.
1 newton gives 1 kg an acceleration of 1 m/s², so 1 N = 1 kg·m/s². Simplified model: no friction, and F means the net force.
F = m × a. Rearrange it into a recipe for a.
Fill the gaps, then the cart tests your recipe: 12 N on 3 kg.
Game: drag race. Tune your car to beat the rival over 100 m.
A bigger motor costs more, and so does a lighter body. Stay within the budget.
Math: each line is a(F) for one cart. Tap the heaviest cart's line.
A 1200 kg car, engine force 3600 N. What is its acceleration in m/s²?
Your race car picks up 300 kg of passengers and luggage. Where does its acceleration land?

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