3.4.1 Force Energy and Momentum Flashcards
Scalars
Quantity with magnitude only
Vectors
Quantity with magnitude and direction and obeys the Law of Vector addition
Conditions for equilibrium
Resultant force equals zero and resultant moment equals zero
Moment about a point
Force x Perpendicular distance between that point and the line of action of the force
Couple
A pair of equal and opposite coplanar forces
Moment of a couple
Force x Perpendicular distance between the lines of action of the forces
(Magnitude of one of the forces)
Principle of moments for equilibrium
The sum of the moments is zero; when the anti-clockwise moments equal the clockwise moments about any point
Centre of Mass
Point on or off a body where the mass appears to be concentrated
Centre of gravity
Point on or off a body where the weight appears to act from
Velocity
Rate of change of displacement
Speed
Rate of change of distance
Acceleration
Rate of change of velocity
Newton’s first Law
When external forces on a body are balanced the body either remains at rest or at a constant velocity
Newton’s second Law
The unbalanced force acting on a body
Is directly proportional to the rate of change of momentum of that body
And is in the same direction as the momentum change
Newton’s third Law
All forces come in equal and opposite pains and act on different bodies
Conservation of linear momentum
In any interaction the total momentum of the system remains constant provided no external forces act
Are under a force time graph
Impulse
Area under a force displacement graph
Work
Power
Rate of doing work
P=Fv
Principle of conservation of energy
The total energy of an isolated system remains constant
