Mechanics Flashcards
What property does a scalar quantity have?
Magnitude only.
What properties do vectors have?
Both magnitude and direction.
Examples of vector quantities:
Velocity, displacement, acceleration, forces, momentum, weight, moments.
Examples of scalar quantities:
Speed, distance, electrical power, charge, mass, energy, current, potential difference.
Speed is…
…rate of change of distance.
Velocity is…
…rate of change of displacement.
Acceleration is…
…rate of change of velocity.
Equation for acceleration using velocities:
a=Δv/Δt
What is unit acceleration measured in?
ms^-2
The gradient of a velocity time graph represents what?
Acceleration.
The area under a velocity time graph represents what?
Displacement.
Define a moment.
The turning effect of a force at a distance perpendicular to the force.
Equation for moments:
M = Fd
Where:
M is the moment.
F is the force.
d is the distance perpendicular to the force from the pivot.
Moments are measured in what?
Nm.
Centre of mass is what?
The mean position of the mass of an object.
Centre of gravity is what?
The position at which weight acts if the object is considered as a single position; the point at which there is no moment due to weight.
In a uniform gravitational field, what can be said about the centre of mass and the centre of gravity?
They are in exactly the same place.
An object is stable, when?
If the line of action from the centre of gravity lies within the base of the object.
How can an object be made more stable?
An object can be made more stable by lowering the centre of gravity or by widening the base.