F = m a


F = force (N)

m = mass (kg)

a = acceleration (m / s / s) or



Mass and weight

Uniform movement

Accelerated movement

Work / energy

Kinetic energy





Pressure and force

Elastic force (Hooke's Law)

Projectile motion



Force is the kind of thing which everybody seem to know what it is.

 Example: Jedis are the ones that have the force!!!

However, in physics,it has a very precise meaning.

According to Newton's Law: F = ma

We can also give a definition:

Force is something that makes an object (or microscopic particle) move or stop to move. On the absence of forces, the object stays as it is , i. e., either moving at a constant speed or stationary.

The important thing to understand from the definition is that a force is not needed to keep an object moving. You only apply a force if you want to stop it or to accelerate it .

In Newtons own words:

"Every object continues in its state of rest, or of uniform motion in a
straight line, unless it is compelled to change that state by forces
impressed upon it."

Newton's first law of movement



1) What force is needed to apply to a car , whose mass is 1000 kg, to provide an acceleration of 10 m/s/s ?

F = m a = 1000*10 = 10000 N

2) What is the force of gravity acting in a person whose mass is 50kg?

acceleration of gravity = g = 10 m/s/s

F = 50 * 10 = 500 N

This force is called weight.


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