Pre AT1 Flashcards
(29 cards)
Describe Negative Acceleration with positive velo
The object is moving forward/positive direction) and the acceleration is moving backwards/negative direction. Therefore, since the acceleration is acting against the forward movement of the object, it slows the object down over time.
(e.g. a car moving forward but braking)
Describe Negative Acceleration with negative velo
The object is moving backwards (left or down/negative direction) and the acceleration is moving backwards aswell. Therefore, since the acceleration is alongside the backward motion of the object, it speeds the object up over time.
(e.g. a car reversing but then it starts pressing the accelerator)
Describe Instantaneous Velocity (usually just velocity unless told otherwise) and give an example
The speed of an object at a certain point in time, meaning it can change from one instant to another
e.g. a cars speedometer shows the instantaneous velocity at that moment
Describe Average Velocity (noted as V with a line above it, or as Vₐᵥ)
The rate of motion in a specific direction (vector) calculated over the entire time period, meaning it doesn’t account for any changes in velo over the journey.
Describe what a frame of reference is
A frame of reference is the perspective from which motion is observed/ measured. It’s almost like a POV. If youre looking at something from a chosen FoR, its like that chosen FoR is the ‘viewing position’ on how objects move.
Define a Scalar Quantity
A scalar quantity includes only a unit and a size/magnitude.
E.g. Time, distance, volume, sped
Define a Vector Quantity
A vector quantity includes a unit, the size/magnitude, and a direction.
E.g. Displacement, Velocity, Force, Acceleration
How is vector quantities in diagrams shown
A vector quantity is represented graphically in the form of an arrowed line segment, with its length corresponding to the magnitude of the quantity it represents, and points in the direction the quantity is acting (Right for East)
Define Distance
A scalar quantity that describes the total length of the path covered in an objects entire journey, regardless of direction.
Define Displacement
Displacement is a vector quantity that indicates the change in position of an object. Instead of following the whole path from point A and B (distance), it only refers to the distance between point A and B.
Define Speed
The change of its position with respect to time. Its measured in ms^-1 (metres per second)
Define Velocity
Change of displacement with respect to time. Its measured in ms^-1 (metres per second)
Relative Velocity
The velocity of an object compared to another within the same frame of reference. It described how fast one moves relative to another
Time Conversion
Seconds –> Minutes (Divide by 60)
Minutes –> Hours (Divide by 60)
Hours –> Day (Divide by 24)
Minutes –> Second (Times by 60)
Hours –> Minutes (Times by 60)
Day –> Hours (Times by 24)
Average Speed and Velocity Formula =
distance/time = s/t
km/h Conversion
km h^-1 (Km/h) –> m s^-1 (m/s) (Divide by 3.6)
m s^-1 –> km h^-1 (Times by 3.6)
Velocity Formula (for non-accelerated motion) =
Displacement/time = Δx/Δt
Acceleration formula =
Change in Velocity over time = Δv/Δt
or v-u / t
In a distance - time graph, what does the gradient/slope =
Speed
In a displacement - time graph, what does the gradient/slope =
Velocity
Simple Displacement Formula
S = Sf – Si
(S - displacement)
(Sf - final position)
(Si - initial position)
Displacement Formula when Initial Velocity, Acceleration, and Time Values are specified
S = ut + ½ at^2
(S - displacement)
(u = initial velocity)
(t = time)
(a = acceleration)
Displacement Formula when Velocity and Time Values are Specified
S = ½(u + v)t
(u = initial velocity)
(v = final velocity)
(t = time)
Relative Velocity between points A and B can be found by:
Va rel b = Va - Vb
(the a rel b is meant to be smaller and to the bottom right of V)
