4. Mechanics Flashcards
(15 cards)
What is the principle of moments?
For a body to be in equilibrium, the sum of clockwise and anticlockwise moments about any point must be equal. If the moments aren’t balanced, the object will turn.
What is a couple?
A pair of forces of equal size that act parallel to each other but in opposite directions. Doesn’t result in any liner force.
What is the centre of mass?
A point through which all the mass of an object is considered to act through regardless of its orientation.
What causes an object to topple, centre of mass wise?
When the direction of the force of weight acting from an objects centre of mass falls outside the objects base area, as this means that a moment is created.
What is the area under an acceleration - time graph?
The total change in velocity.
What is Newton’s first law of motion?
The velocity of an object will not change unless a resultant force acts on it.
What is Newton’s second law of motion?
F = ma
What is Newton’s third law of motion?
Each action has an equal and opposite reaction.
What is friction, and what are the two kinds?
- A force that opposes the direction of travel.
- Friction usually refers to solid objects, but there is also fluid friction which depends on the viscosity of the fluid, the speed, and the shape of the object.
- Friction converts kinetic energy to heat.
What is lift?
An upwards force perpendicular to the direction of the flow of fluid.
What is terminal speed?
When frictional forces equal the driving forces there’s no acceleration.
What is the equation for momentum?
p = mv
Is momentum conserved in inelastic collisions?
No, unless it is linear momentum, in which case it is.
What is the formula for impulse?
FΔt = Δ(mv)
How can kinetic and potential energy be related in a closed system?
Change in potential energy = change in kinetic energy.
