Forces In Action Definitions

Physics A Level OCR A

Newton

Force that will produce an acceleration of 1 ms^-2 when acting on an object of 1 kg mass

Centre of gravity

The point at which the weight of an object acts

Drag

resistive force on an object travelling through a fluid

Pressure

The normal force exerted per unit cross-sectional area

normal contact force

force acting when one object rests upon each other (in the case where the forces are in equilibrium, e.g., not accelerating)

Archimedes Principle

The upthrust exerted on a body immersed in a fluid is equal to the weight of the fluid that the body displaces.

Power

rate of work done = rate of energy transferred

Newton’s First Law

an object will remain at rest or continue to move with constant velocity unless acted upon by a resultant force

Newton’s Third Law

when two objects interact, they exert equal and opposite forces on eachother

Principle of momentum

In a closed system, the total momentum in a specified direction remains constant

Elastic collision

conserves momentum, total energy and KE

Inelastic Collision

Conserves momentum, total energy but NOT KE

Newton’s 2nd Law:

The resultant force acting on an object is directly proportional to the rate of change of momentum, and is in the same direction

Impulse

product of force and the time for which the force acts on an object = change in momentum