MECHANICS Flashcards
Centre of mass
The single point through which all the mass of an object acts.
Conservation of energy
Energy cannot be created or destroyed - only transferred into different forms
Conservation of momentum
Momentum before = momentum after
Couple
Two equal and opposite parallel forces that act on an object through different lines of action, causing rotation
Density
Mass per unit volume
Equillibrium
The resultant force and resultant moment acting on the object must be zero
Impulse
The change of momentum of an object when a force acts on it. Force * time
Moment
The product of a force and perpendicular distance from the line of action to the force
Momentum
Product of an object’s mass and velocity
Newton’s 1st Law
An object will remain in constant motion or equilibrium until acted on by a resultant force
Newton’s 2nd Law
The sum of forces acting on an object is equal to rate of change of momentum of the object.
Newton’s 3rd Law
Every force has an equal and opposite reaction force
Terminal speed
The maximum speed of an object that occurs when the resistive and driving forces are equal
Angular speed
A measure of the speed of an object’s angular rotation
Centripetal acceleration
Acceleration of an object moving in a circle
Centripetal force
The resultant force responsible for keeping an object in circular motion, acts towards the centre of the circle
Critical damping
Damping that reduces the displacement of an oscillating object in the quickest time possible without further oscillation.
Damping
Dissipation of energy from an oscillating system.
Forced vibrations
Repeated up and down vibrations, at the frequency of a driver. The amplitude of oscillation is small at high frequencies and large at low frequencies
Free vibrations
Vibrations not caused by a driver. An object will naturally oscillate at its natural frequency
Overdamping
A type of damping where the system is damped more than necessary, and so it takes longer for it to return to equilibrium position
Resonance
When the frequency of oscillations is equal to the natural frequency of an oscillating frequency. The rate of energy transfer is at a maximum during resonance
Simple harmonic motion
Motion where the acceleration of an object is directly proportional and opposite to the displacement
