The motion of an object can change
only if forces act on it.
Forces (pushes or pulls) are vector
quantities -- they have size and direction.
The acceleration of an object
equals the net force on it, divided by the object's mass.
The free body diagram is a tool
for analyzing the forces acting on an object.
In order for an object to round
a curve, there must be an acceleration on it toward the center of the curve.
If the curve is the arc of a circle, this acceleration is:
