Hello everyone! Today, we’re going to cover a major aspect of animation
Physics!
Physics is a major aspect to consider when animating
it gives the animation a more realistic feel
and allows for the viewer to understand and connect with what’s going on.
Here are several topics we’ll be going over today
According to Newton’s 1st Law of Motion,
objects in motion stay in motion
and objects at rest stay at rest
unless acted upon by an external force.
The Law of Inertia (Newton’s 1st Law) can be displayed with someone on a moving platform.
In this scene, I sit on a cart as Capa pushes it.
When Capa begins pushing the cart, I move backwards until a force stops me
When the cart comes to a halt, the same happens.
This is what we call “drag”
essentially when objects follow (or ‘drag’ in this case) with an initial action.
It’s also known as “overlapping action”,
as the movement of the second object goes at a different time as the first object.
This ties in with our second topic, constant velocity.
Anything with constant velocity maintains a straight path of motion
and moves with constant timing.
Objects moving during certain instances would maintain constant velocity.
Take these for example:
Each step Emily takes contains the same amount of frames.
When she speeds up or slows down, the number of frames change. (tf happened to my grammar)
Of course any object needs to accelerate or decelerate at some point when it:
exerts a force by itself
or, an external force is being exerted onto it.
As seen with the previous walking animation,
the movement of the walk follows a wave like pattern.
Accelerating when going down,
maintaining constant speed in the middle,
and decelerating at the end.
The movement of any object may alter depending on the surface it’s on.
For example, a box being moved across a smooth surface will require less force and will accelerate faster
compared to it moving on an uneven one.
Alright, before we get into forces,
we have to cover momentum first.
All moving objects have momentum, which depends on their speed and weight.
Unbalanced forces change momentum,
the size of the force helps determine this.
It can affect the speed and timing of the action,
or create a change in direction.
So, the larger the force, the quicker the momentum changes.
A person throwing a punch.
In the first few frames, the person winds their arm back, generating energy.
Based on how far their arm is pulled back, the viewer can anticipate how much force
the character puts into their action.
They then turn their chest and move their body slightly forward
before their arm follows through with the rest of the punch, releasing the energy.
The act of the arm following through can be described as a change in momentum.
Due to this action requiring a great amount of force,
the acceleration’s speed is increased compared to when the arm pulled back.
As briefly mentioned in the previous example,
emphasis on a subject’s actions shows how much force is being applied or used.
We can ask ourselves, “How much force do we want the character to apply?”
Do we want them to exert a great amount of power?
Or just barely any?
As the force acting upon an object is increased,
the acceleration of the object is increased.
As the mass of an object is increased,
the acceleration of the object is decreased.
Take a small person and a large person bumping into each other.
They can be applying the same force initially,
but their acceleration or force after coming in contact differs.
The force the smaller person experiences will be much greater than the larger person’s.
So, they’ll be pushed back more.
“For every action, there is an equal and opposite reaction.”
n this scene, I start off by exerting a force onto Capa.
yEET
She’s then pushed over and falls down depending on how much force was exerted.
However, I don’t stop there,
as I get pushed back slightly due to an opposite force being applied.
Certain objects in motion “gain” and “lose” weight.
How so?
Well, when moving with gravity, the subject seems to lose weight,
and when they move against gravity, they seem to gain weight.
Emily prepares her jump by first crouching down slightly.
Here, she moves with gravity, speeding up while falling, thus “losing weight”.
She then propels herself upwards,
she goes against gravity as she rises up and speeds up, “gaining weight”.
When launched into the air, she’s still rising but instead slows down, due to deceleration.
As Emily falls, she accelerates downwards from her highest point.
Finally, when she lands, she slows down again to end the action.
Thank you everybody for watching!
If you feel like we left some things out, let us know!
We hope you’ve learned more about animation and the physics going behind it.
