Studied by 0 people
Looks like no one added any tags here yet for you.
Scalars vs. Vectors → what’s the difference?
A scalar is a measurement that only has magnitude (size), but no particular direction. Some examples are:
Speed
Distance
Temperature
Volume
Mass
Energy
A vector is a quantity that has both direction and magnitude. Some examples are:
Velocity
Displacement
Weight (force due to gravity)
Momentum
Distance vs. displacement → what’s the difference?
Distance (s) - is the length between two points
Displacement (s^→) - is the position of an object relative to the origin or starting point. It must be given a positive or negative value to show which side of the origin the object is positioned. It has both direction and magnitude, and therefore is a vector quantity
For example: if a marathon of 42.2km starts and finishes at the same line, distance = 42.2, where as displacement = 0.
Both distance and displacement are measured in S.I. unit: metres (m)
Distance-time graphs and how to read them
Displacement-time graphs and how to read them
Movement and time intervals
Movement is measured as the change of position in the time interval
The time interval is shown as Δt, there Δt = t(final) - t(initial)
It represents the amount of time that has passed from one measurement to the next
The unit of measurement for time is seconds (s)
Speed vs. velocity → what’s the difference?
Speed (v) - is the distance covered in a time interval.
It is a measure of how fast something is travelling. It can be measured by observing the distance travelled and dividing by the observed time taken.
Formula: v = s/t
Velocity (v^→) - is the change in displacement in the time interval, and therefore is a vector quantity.
Speed is the magnitude of the velocity
Velocity also includes direction
Speed-time graphs and how to read them
Average speed vs. instantaneous speed - what’s the difference
Average speed is the one single speed that would enable an object to cover a specified distance in a given time interval.
Formula: v(avg) = s/Δt
Where the average speed = distance/Δtime
Instantaneous speed is the rate at which distance is covered over a time interval that is so brief as to be negligible.
For example: a car’s speed at a certain moment is its instantaneous speed. If the time interval was very small, the average speed becomes very close the the instantaneous speed.
So if t = low, v(inst) ≈ v(avg)
Relative velocity
Relative velocity depends on the frame of reference
Formula: velocity(observer) - velocity(other object)
If objects are travelling in opposite directions, the velocity(observer) - velocity(other object) will necessarily yield a positive number.
Whether they are
closing or separating will depend on their initial positions, but the relative velocity will have the same
magnitude.
Velocity-time graphs and how to read them
Acceleration vs. deceleration
The both involve a change in speed over time; Δvelocity/Δtime.
Acceleration is the positive change of velocity over time, this means that the velocity is increasing.
Deceleration is the negative change of velocity over time, this means that the velocity is decreasing.
a(avg) = Δv/Δt
Acceleration is measured in m/s/s/ or ms^-2
