Forces & Motion + Energy & Momentum - Physics Equations

Displacement:

Straight line distance from a point in a given direction. It is a vector quantity.  

Speed:

The rate of change of distance 

Velocity:

The rate of change of displacement. It is a vector quantity. 

Acceleration:

The rate of change of velocity. It is a vector quantity. 

Mass:

The property of an object that resists change in motion 

Inertia:

The tendency of an object to carry on moving 

N1L:

An object remains at rest or travels at a constant velocity unless acted on by a resultant force 

N2L:

Resultant force is proportional to (or equal to) the rate of change of momentum 

N3L:

When two bodies interact, the forces they exert on each other are equal in size and opposite in direction 

Weight:

Is the effect of a gravitational field on a mass 

Moment

The moment of a force about a point is the product of the force and perpendicular distance from the line of action of the force to the point 

Torque (of a couple):

The product of one of the forces and the perpendicular distance between the forces.  

Principe of moments:

The sum of the clockwise moments about a point is equal to the sum of the anticlockwise moments about the same point provided the body is in equilibrium 

Equilibrium:

When there is no resultant force and no resultant torque, a system is in equilibrium. 

Centre of Gravity:

The point where the entire weight of an object appears to act.  

Mass

Is a property of an object that resists a change in motion 

Momentum:

Is a product of mass and velocity 

Force:

Is the rate of change of momentum (N2) 

Principle of conservation of momentum:

The total momentum before a collision is equal to the total momentum after a collision 

Principle of conservation of energy:

Energy is neither created or destroyed but transferred from one store to another. 

Efficiency:

Is the ratio of the useful energy output from the system to the total energy input