Mechanics Flashcards
What is a scalar quantity?
A quantity that has magnitude but no direction.
What is a vector quantity?
A quantity that has BOTH magnitude and direction
What is equilibrium?
If an object is in equilibrium, all of the forces acting on the object are balanced and cancel each other out.
What is a moment?
The turning effect of a force.
What is a lever?
Where an effort force is applied to a load force by means of a rigid object rotating around a pivot.
What is a couple?
A pair of forces of equal magnitude that act parallel to each other but in opposite directions.
What is the centre of mass of an object?
A single point that you can consider the whole weight to act through.
How do you find the centre of mass of an object?
1) Hang the object freely from a point.
2) Draw a vertical line downwards from the point of suspension - use a plumb bob to get your line exactly vertical.
3) Hang the object from a different point and draw another line.
4) The centre of mass is where those two lines intersect.
What is speed?
How fast something is moving, regardless of direction.
What is displacement?
How far an object’s travelled from its starting point in a given direction.
What is velocity?
The rate of change of an objects displacement.
What is acceleration?
The rate of change in velocity.
What does the gradient of a displacement-time graph represent?
Velocity
What does the gradient of a velocity-time graph represent?
Acceleration
What does the area under a velocity time graph represent?
Displacement
What is Newton’s first law?
The velocity of an object will not change unless a resultant force acts on it.
What is Newton’s second law?
F = ma
What is Newton’s third law?
If an object A exerts a force on object B, then object B exerts an equal but opposite force on object A.
What is freefall?
Freefall is where the only force acting on an object is gravity.
What is friction?
A force that opposes motion.
What is terminal speed?
When the frictional forces acting on an object is equal to the driving force.
What is lift?
An upwards force on an object moving through a fluid.
What is momentum?
The product of mass and velocity.
What is the principle of moments?
The sum of the clockwise moments is equal and opposite to the sum of the anti-clockwise moments.
What is an elastic collision?
Where momentum and kinetic energy are conserved, no energy is dissipated as heat, sound.
What is impulse?
Defined by the product of force and time.
What is work done?
Energy transferred.
What is power?
The rate of doing work.
What does the conservation of energy state?
Energy cannot be created or destroyed. Energy can be transferred from one form to another but a total amount of energy in a closed system will not change.
What is an inelastic collision?
Where momentum is conserved but kinetic energy is not conserved. Energy is dissipated as heat and sound.
