- For no net force, an object at rest remains at rest.
- An object moving at constant velocity continues moving at constant velocity.

- Σ
**F**= m**a.** - In components: ΣF
_{x}= ma_{x}and ΣF_{y}= ma_{y}.

For constant net force and motion beginning at t=0: a_{x}= ΣF_{x}/m
a_{y}= ΣF_{y}/m.

Then the equations of motion, or the kinematic equations, are:

- v
_{x}(t) = v_{x}(0) + a_{x}t - x(t) = x(0) + v
_{x}(0) t +½ a_{x}t^{2}

- v
_{x}(t)^{2}= v_{x}(0)^{2}+ 2 a_{x}[x(t) - x(0)]

- x(t) = x(0) +½ [v
(0) + v _{x}(t)] t

and similarly for the y-direction.

IMPORTANT: Keep the
x-component and y-component equations separate! The only attribute common to
both sets of equations is the time.