Mechanics Flashcards
Centre of mass
Point where the total mass of an object is said to act
Conservation of energy
In a closed system with no external forces, the energy of the system before the event is equal to the energy of the system after
Conservation of momentum
In a closed system with no external forces, the total momentum of the system before the event is equal to the momentum of the system after
Drag
Resistance against motion of an object through a fluid
Efficiency
Useful output / total output
Elastic collision
Kinetic energy of a system before the event is equal to the kinetic energy of the system after
Equilibrium
When the moments about a point are balanced and the resultant force is zero
Force
Rate of change of momentum of an object
Product of an object’s mass and acceleration
Friction
Resistance against the motion of an object
Inelastic collision
Kinetic energy of a system before the event is not equal to the kinetic energy of the system after
Lift
A force acting perpendicular to the flow of air or liquid around an object, typically upwards
Moment
Product of a force and it’s perpendicular distance from the pivot
Momentum
Product of an object’s mass and velocity
Newton’s 1st Law
Object will remain at a constant velocity unless acted on by a resultant force
Newton’s 2nd Law
Force = Mass x Acceleration
Newton’s 3rd Law
Every action has an equal and opposite reaction
Power
Work done by a system divided by time taken
Resultant force
Sum of all forces on an object
Scalar
Quantity with only magnitude, no direction
Terminal velocity
Maximum velocity an object can achieve
Vector
Quantity with magnitude and direction
Weight
Force of gravity on an object, W = mg
Work done
Force applied over a distance
Energy transferred in that distance
