2.1 - Motion Flashcards
How do we calculate rate of movement (speed)
Speed = distance / time
V = d/t
What is velocity
When you include the direction in the information about the rate of movement of an object - this is velocity
It’s the rate of change of displacement - wher the distance in a particular direction is called the displacement
What’s displacement
The distance in a particular direction
How is velocity calculated
Velocity = displacement / time
V = s/t
Or v = little triangle s / little triangle t
What’s a vector
A quantity in which the direction must be stated is known
What’s a scalar quantity
If direction is not important - the measurement is referred to as a scalar quantity
How are vectors notated ? (Idk if it’s just the way the book does it or if it’s true irl lol)
Vector notation means that vectors are written in bold type to distinguish them from scalar variables
How is average speed calculated
Calculated by dividing the total distance for a journey by the total time for the journey - thus it averages Out the slower and faster parts off the journey and even includes stops
What’s acceleration
It’s defined as the rate of change of velocity, therefore it must include the direction in which the speed is changing and so acceleration is a vector quantity
How can we calculate acceleration
Change in velocity / time taken to change the velocity
a = (v - u)/ t
What is the vector nature of acceleration
If an object changes just the direction of its velocity, it’s accelerating whilst remaining at a constant speed
Similarly, deceleration represents a negative change in velocity and so could be quoted as a negative acceleration
What’s the greatest speed possible
No speed or velocity can ever be greater than the speed of light which is 3 x 10^8 m/s
If one calculates a speed higher than this, one must be wrong m8 ya idiet
Define speed
The rate of change in distance
Define velocity
The rate of change of displacement
Define displacement
The vector measurement of distance in a certain direction
Define a vector
A vector quantity must have both magnitude and direction
Define a scalar
A scalar quantity only has magnitude
Define average speed
Calculated by dividing the total distance for a journey by the total time for the journey
Define instantaneous speed
Is the speed at any particular instant in time on a journey, can be found from the gradient of the tangent to a distance time graph at that time
Define acceleration
Is the vector defined as the rate of change of velocity
How can a velocity time graph be generated
Can be produced from direct measurements of the velocity or generated from calculations made using a displacement time graph
What da difference with displacement and distance graphs against time
Displacement time graphs can have a decreasing displacement y value whereas a distance time graph y value can only increase !
What can we find out from displacement time graphs / distance graph
Simplest thing is how far an object has moved in a certain amount of time
A flat line bit means the object is stationary
The gradient tells us the speed - found from the ratio of change of y axis divided by x axis
- distance / time
Or displacement / time
What does a velocity time graph show
Shows the velocity of an object over time
For velocity we can also tell the direction with the y value being positive or negative