NSTA Web Seminar Force and Motion Bill Robertson February 1, 2006. Newton’s third law Circular motion. Newton’s second law. Σ F = ma Σ F: represents the net force acting on an object. m: represents the mass of an object, which is a numerical measure of its inertia.
Newton’s third law
ΣF = ma
ΣF: represents the net force acting on an object.
m: represents the mass of an object, which is a numerical measure of its inertia.
a: represents the acceleration of the object.
Suppose you want to figure out all the forces acting on something that's moving in a circle, such as a race car rounding a curve at constant speed.
Should you do the following? Figure out all the forces of contact on the car, such as friction, and then add the centripetal force to these forces.
The centripetal force is a name given to forces that are already present, that happen to cause something to move in a circle. In this case, the friction between Einstein and the record is the force causing Einstein to move in a circle. Therefore, friction is the centripetal force.
When you view things from a rotating frame of reference, a centrifugal force appears. This force is very real to someone in that frame of reference.