Mechanics Definitions

Question	Answer
Scalar vs. Vector	A scalar quantity is one of magnitude, whereas vectors have both magnitude and direction.
A Moment	Of a force, is the force multiplied by the perpendicular distance from the pivot, to the force's line of action.
Principle of Moments	For an object in equilibrium, the sum of the clockwise moments - about a point - must equal the sum of anti-clockwise moments about the same point.
Centre of Gravity	The point at which all weight can be considered to act.
Centre of Mass	The point at which all mass can be considered to act.
Torque of a Couple	Two forces balance so the object does not move, but the object is not in equilibrium. The pair of forces cause it to rotate - and are called a couple.
Equilibrium	For an object to be in equilibrium, resultant force and torque must equal 0.
Speed	Distance per unit time.
Instantaneous Speed	The speed at the moment it is measured.
Velocity	Displacement per unit time.
Acceleration	The rate of change of velocity.
Projectile Motion	Any object acted upon only by the force of gravity, hence verticle and horizontal motion can be treated independently since they are acting at 90° to each other.
Newton's 1st Law	An object will remain at rest or in uniform motion unless acted upon by a new force.
Newton's 2nd Law	The force required to accelerate a particle is equal to the product of the mass of the object and the acceleration needed.
Newton's 3rd Law	For every action, there is an equal and opposite reaction.
Momentum	Mass multiplied by velocity.
Principle of Conservation of Momentum	For a system of interacting objects, the total momentum remains constant provided no external force acts on the system.
W	Force multiplied by the distance moved in the direction of the force.
Principle of Conservation of Energy	Energy can't be created nor destroyed, only converted between forms.
Power	The rate of work done.

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Mechanics Definitions

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	Created by Lauren Blood about 7 years ago