In the previous section, we learned to calculate net force and acceleration.
That calculation is the basis of dynamics, the science of explaining why things
move the way they do.
The next several sections on quantitative dynamics will follow a similar pattern:
looking at a situation, drawing a quantitative freebody diagram of that situation,
and using it to analyze that situation.
We will start with the simplest two freebody diagrams:
a block at rest on a table,
and a block being pulled on a frictionless table.
These are certainly not the most exciting examples,
but they give us a good opportunity to start using the methods and vocabulary of
dynamics.
Crucial to this section is to understand how to use vectors.
The forces on all of our freebody diagrams are vectors,
meaning they have magnitude and direction,
and none of our freebody diagrams are complete until we correctly know the magnitude
and direction of every force!
Force 1: Gravity
Gravity is a force that attracts all mass to all other masses,
but of course, here on earth, gravity is a force that always pulls you down.
Sometimes, the force of gravity when here on earth is called the weight.

On earth, the direction of gravity is always down.

On earth, the magnitude of gravity is given by the formula \( F_g = m g \).
$$
F_g = mg
$$
Force 2: Normal Force

The direction of the normal force is always perpendicular to the surface.
For these problems, the direction of normal force will be up.

For now, the magnitude of the normal force will equal the magnitude of
gravity. But know that in the future it will get much more complicated!

A block is resting on a table.
It has a mass of 2 kg.

Fill out the table below to draw a complete freebody diagram of the block.

Use your freebody diagram to determine the net force \( \Sigma F \)
acting on the block.

Determine the acceleration \( a \) of the block.

A block is resting on a table.
It has a mass of 5 kg.

Fill out the table below to draw a complete freebody diagram of the block.

Use your freebody diagram to determine the net force \( \Sigma F \)
acting on the block.

Determine the acceleration \( a \) of the block.
Force 3: Applied Force
An applied force is any force applied
an on some object by a human.
Common examples are pulls and pushes.
The applied force is frequently a given value
in a problem. That is, both magnitude an direction
are often given in a problem.

An object with a mass of 2.00 kg is being pulled on a frictionless table.
It is pulled with an applied force of 16.0 Newtons.

Fill out the table below to draw a complete freebody diagram of the block.

Use your freebody diagram to determine the net force \( \Sigma F \)
acting on the block.

Determine the magnitude of acceleration \( a \) of the block.
Please write formulas before using them.

An object with a mass of 3.56 kg is being pulled on a frictionless table.
It is pulled with an applied force of 12.6 Newtons.

Fill out the table below to draw a complete freebody diagram of the block.

Use your freebody diagram to determine the net force \( \Sigma F \)
acting on the block.

Determine the acceleration \( a \) of the block.
Please write formulas before using them.