Scalars and Vectors Flashcards
What is a scalar?
A quantity with magnitude only
What is a vector?
A quantity with magnitude and direction
Examples of scalars (6)
Mass, distance, volume, density, time, speed
Examples of vectors (4)
Displacement, velocity, acceleration, momentum
What is displacement?
The shortest distance between two points with the direction
Mean and instantaneous speed?
Mean speed = total distance travelled/total time taken
Instantaneous speed = rate of change of distance with time
Mean and instantaneous velocity?
Mean velocity = total displacement/total time taken
Instantaneous velocity = rate of change of displacement with time
Mean and instantaneous acceleration?
Mean acceleration = change in velocity/total time taken
Instantaneous acceleration = rate of change of velocity with time
Equation of a moment
Moment = Force X Perpendicular distance from a pivot
Equation of moments in equilibrium
Resultant clockwise moments
=
Resultant anti-clockwise moments
How do you find the perpendicular distance? Equation?
Look along the tension force line and draw a perpendicular line to the pivot
d = (a sin 🔘) X t
2 conditions needed for equilibrium?
- the resultant force is zero in any line
- the net moment is zero around any pivot
Principle of moments?
If an object is in equilibrium, then the resultant moment around any point point is zero
What is the centre of gravity?
The pint in which all weight is considered to act
What is density and its equation?
“Mass per unit volume”
Density = mass/volume
