# Inertia

Inertia is a property of objects that makes them want to keep doing what they are already doing. So, if an object is standing still, it will want to stay still unless something pushes or pulls it. And if an object is moving, it will want to keep moving in the same direction and at the same speed unless something slows it down or changes its direction. This is why characters in animations need a force to start moving and a force to stop them or change their movement.

Inertia is a fundamental concept in animation that allows animators to create realistic and believable movements. It plays a crucial role in creating the illusion of weight, mass, and gravity, making the animations more immersive and engaging.

One of the primary uses of inertia in animation is to simulate the movement of objects. When an object is set into motion, it continues to move with the same speed and direction until an external force acts upon it. This principle is known as Newton’s first law of motion, and it applies to both real-world physics and animation.

For example, when animating a ball rolling down a slope, the animator needs to take into account the ball’s initial velocity and momentum. The ball will continue to roll down the slope until it reaches a flat surface or encounters an obstacle that slows it down or changes its direction. By incorporating these physical principles into their animations, animators can create more realistic and believable movements.

Another way animators use inertia in their work is by giving characters weight and mass. When an animated character moves, its body parts will continue to move for a short time before coming to a complete stop because of inertia. This effect is particularly noticeable when characters perform quick movements such as jumping or running.

By adding weight and mass to their characters, animators can make the movements more convincing and grounded in reality. For example, if a character jumps off a high platform, they will fall faster than if they jumped off a lower platform due to gravity. Similarly, if a character runs too fast on a slippery surface, they might lose their balance and slide for some distance before coming to a stop.

Inertia also plays a significant role in simulating collisions and impacts. When two objects collide in real life, they will bounce off each other or crumple depending on their relative masses and velocities. Animators can replicate this effect by using physics simulations that take into account the objects’ physical properties such as mass, elasticity, and friction.

By incorporating inertia into their animations, animators can create more realistic and believable movements that accurately reflect how objects and characters behave in the real world. This makes the animations more immersive and engaging for viewers, enhancing the overall quality of the animation.

## Animation Terms

2D Animation

3D Animation

Alpha Channel

Ambient sound

Animation

Anti-Aliasing

Anticipation

Aspect Ratio

Bezier Curve

Bitmap

Blue Screen

Bone Animation

Bounce

### C

Camera Angle

Camera Shake

Casting

Cel Animation

Character Animation

Character Design Sheets

Cinematic lighting

Claymation

Clean-up

Close-up

Color Correction

Compositing

Composition

Concept Art

Continuity editing

Cross-cutting

Cut

Cutout nimation

### D

Depth of Field

Dialogue

Dissolve

Distributed Rendering

Dolby Atmos

Dope Sheet

Dutch Angle

Easing

Emitter

Exaggeration

Eyedropper

### F

Foley

Forward Kinematics

Frame Rate

Frame

Framing

Freeze Frame

Ghosting

GIF File Format

Golden Ratio

Graph Editor

### H

High key lighting

Hue and Saturation

### I

Inertia

Infographic Animation

Inverse Kinematics

Joint

JPEG File Format

Jump cut

### K

Keyframe Interpolation

Keyframe

Kinetic typography

Layers

Lens distortion

Level of Detail

Lighting

Line of action

Lip syncing

Low key lighting

Match cut

Matte painting

Montage

Morphing

Motion blur

Motion capture

Motion graphics

Motion path

Motion trail

Mouth shapes

MP3 File Format

MP4 File Format

### N

Network rendering

Non-linear editing

### O

Occlusion culling

Onion skinning

Overlapping action

### P

Pan

Parallel rendering

Particle system

Persistance of Vision

Phonemes

Playback speed

Plot

PNG File Format

Pose-to-pose animation

Props

Puppet animation

Render farm

Rendering

Resolution

Rigging

Rotoscoping

Rule of thirds

Run cycle

### S

Safe zone

Scene

Score

Screenplay

Script

Shot

Silhouette

Skeletal animation

Slow Motion

Smears

Sound Design

Sound effects

Soundtrack

Special Effects

Split screen

Squash and Stretch

Staging

Stop Motion Animation

Storyboard

Time Remapping

Timeline

Timing

Title Card

Title Sequence

Tracking shot

Tweening

### V

Vector graphics

Visemes

Voice acting

Voice-over Narration

Walk cycle

WebM File Format

Weighting

Wide shot

Z-depth

Zoom