Give your animations the correct weight and impact! In this 2D animation lesson for beginners we dive into the basic laws of physics all animators have to know.

Find out…

  • why heavy and light objects deal with forces differently,
  • how speed indicates the scale of your animation,
  • what a bounce tells us about the mass and material of an element.

Watch the video above to see the most important rules of physics in action.

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Resistance of mass – Inertia

Elements like to stay in the state that they are in. This is one of the most important laws of physics and yet for some reason it’s often overlooked in animation tutorials.

Big masses put up a lot of resistance to change their state.

Light masses are less resistant to change their state.

This resistance is the inertia of a mass and influences heavily how you have to animate a character or element:

A big mass needs a lot of force to start, stop and change direction. Small force will not make them move at all.

A small mass needs little force to start, stop and change direction. Small force can send a small mass flying.

Most objects fall the same

Scientists figured out exactly how objects fall in the gravity of earth. Of course there is formula for it. Don’t worry, you don’t need to know it by heart, but we will use it to get a feeling for how objects fall:

d = 1/2 * g * t^2

d is the distance in meters, t is the time in seconds and g the gravity of earth.

Notice how the mass is not included in this formular. This means that many things fall the same regardless of their weight. A massive bowling ball reaches the ground at the same time as an air-filled ping pong ball.

The speed reveals the scale

When we switch some things around we can calculate the time an objects takes to fall for different heights.

t = sqrt(2d / g)

Playing around with some values we get some interesting information.

Objects fall 1.2 m in 0.5 seconds

and 20 m in 2 seconds

2 seconds! That is quite long.