P2.1.1 - AQA GCSE Physics Unit 2

P2.1.1	Resultant forces
	a) Whenever two objects interact, the forces they exert on each other are equal and opposite.	This is Newton's Third Law of Motion
	b) A number of forces acting at a point may be replaced by a single force that has the same effect on the motion as the original forces all acting together. This single force is called the resultant force.	Candidates should be able to determine the resultant of opposite or parallel forces acting in a straight line. Addition of forces that are not co-linear is for A-Level (or more mathermatically skilled) students. Such questions will not be set.
	c) A resultant force acting on an object may cause a change in its state of rest or motion.	This is Newton's First Law of Motion
	d) If the resultant force acting on a stationary object is: ■ zero, the object will remain stationary ■ not zero, the object will accelerate in the direction of the resultant force.
	e) If the resultant force acting on a moving object is: ■ zero, the object will continue to move at the same speed and in the same direction ■ not zero, the object will accelerate in the direction of the resultant force.