3.4.1.3 Motion Along A Straight Line Flashcards
What is speed?
Speed is defined as the change of distance per unit time.
It is the rate of change of distance covered.
Speed is independent of direction, as it is a scalar quantity.
What is average speed? What is the equation?
The total change in distance over the total time.
Equation:
Average Speed = Total Distance Covered / Total Time Taken
What is instantaneous speed? What is the equation?
The objects speed at a particular moment in time.
Equation:
Instantaneous Speed = Change in Distance / Change in Time.
What is constant speed?
Constant speed is when an objects instantaneous speed is always constant. Average speed = instantaneous speed.
What is velocity?
Velocity is defined as the rate of change of displacement.
Velocity is speed in a given direction.
Velocity is a vector quantity, therefore is dependant on direction.
How could an objects velocity change?
The object speeds up
The object slows down
The object changes direction.
What is Average Velocity? Give an equation?
Total change in displacement divided by the total time taken.
Average Velocity = Total Displacement / Total Time Taken
What is instantaneous velocity? Given an equation?
The velocity at a particular moment in time.
Instantaneous velocity = change in displacement / change in time.
What is distance?
Distance is how far an object travels, regardless of the direction it travels in.
It is a scalar quantity.
What is displacement?
Displacement is how far an object travelled from its starting point in a given direction. It is a net change of position, or a net distance moved.
It is a vector quantity.
What equation can be used to calculate displacement?
Displacement = Average Velocity x Time.
What is acceleration?
Acceleration is defined as the change of velocity per unit time.
What is deceleration?
Deceleration is negative values. This signifies that velocity decreases with respect to time.
What is the equation for acceleration?
Acceleration = v - u / t
What are the SUVAT quantities, and their units?
S - Displacement (metres, m)
U - Initial Velocity (metres per second, m/s)
V - Final Velocity (metres per second, m/s)
A - Acceleration (metres per second, per second, m/s^2)
T - Time (seconds, s)
What is the first SUVAT equation? Without Displacement.
v = u + at
What is the second SUVAT equation? Without acceleration?
S = (U + V) / 2 X t
What is the third SUVAT equation? without final velocity/
s = ut + 1/2at^2
What is the fourth SUVAT equation? Without time?
v^2 = u^2 + 2as
What is the fifth SUVAT equation? Without initial velocity?
s = vt - 1/2at^2
What could give an increase in acceleration?
Acceleration could mean a change in speed or direction, or both.
What does the gradient of a distance time graph?
Speed.
Describe the distance time graph for an object with constant speed.
Straight line with a constant gradient.
Describe the distance time graph of an object moving with changing speed.
The gradient of the line will constantly change.
What does the gradient of a displacement time graph show?
Velocity.
What does the displacement time graph for an accelerating object show?
A curve, and constantly changing gradient.
What does the displacement time graph for an object undergoing constant acceleration?
Straight line, constant gradient.
The rate of change of the gradient (velocity) is constant.
What does the s/t curve for an accelerating or decelerating object look like?
If an object is accelerating, the curve has an increasing gradient.
If an object is decelerating, the curve has a decreasing gradient.
What does the gradient of a velocity time graph represent?
Acceleration.
How is uniform acceleration acceleration represented? (velocity time)
It is always a straight line. The steeper the gradient, the greater the acceleration.
How is a constant velocity (no acceleration) shown? (velocity time)
Flat line. No gradient.
What does the area under a velocity time graph represent?
Displacement.
How is non-uniform acceleration represented on a velocity time graph represented?
A changing gradient (a curve)
How is an increasing acceleration represented? (velocity time graph)
An increasing gradient.
How is a decreasing acceleration represented? (velocity time graph)
A decreasing gradient.
What does the gradient of an acceleration-time graph show?
It shows the nature of the acceleration.
What does the graph of an accelerating object show? (acceleration time)
A constant gradient above the x axis.
What does the graph of a decelerating object show? (acceleration-time graph)
Constant gradient below the x-axis.
What does the graph of an object with constant acceleration/deceleration show? (acceleration time).
Flat horizontal line, above or below the x-axis
What does the acceleration/time graph of an object with constant velocity show?
Flat line which lies on the x-axis.
What does a negative gradient above the time axis represent on an acceleration time graph?
It means that the rate of acceleration is decreasing.
What does a positive gradient above the x-axis on an acceleration time graph represent?
It shows the rate of acceleration is increasing.
What does a negative gradient below the time axis represent on an acceleration time graph?
Shows the rate of deceleration is decreasing.
What does a positive gradient below the time axis represent on an acceleration time graph?
It shows the rate of deceleration is increasing.
What is freefall?
Freefall is when there is gravity acting on an object, and nothing else.
It is defined as the motion of an object undergoing an acceleration of 9.81 m/s^2.
What direction does gravity act in?
Gravity acts downwards.
Which is the only force acting on an object in freefall?
Its weight
What is the equation for an objects weight?
Weight = Mass x Gravitational Field strength. W = m x g
How can an object with an initial velocity still undergo freefall?
Objects can have an initial velocity in any direction and still undergo freefall, as long as the force providing the initial velocity is no longer acting.
What is the direction and notation for g?
Upwards, g is positive
Downwards, g is negative.
What are the suvat equations when an object undergoing freefall have no initial velocity.
All values and multiples of U are removed.
a is taken as negative g, so - 9.81.
What are the suvat equation when an object has an initial velocity upwards?
The object is projected upwards, so the suvat equations are normal, with a negative value of g replaced with a.
What are the suvat equation when an object has an initial velocity downwards?
The object is projected downwards, so the suvat equations are normal, with a negative value of g replaced with a.
