Module 3.1 - Motion Flashcards
Define displacement
Distance moved in a particular direction from a reference point
Define instantaneous speed
The speed at an actual point in time during a journey. This value changes at various points in a journey.
Define average speed
The total distance travelled divided by the total time taken for a journey. These values do not change.
Define velocity
Displacement per unit time
Define acceleration
Change in velocity per unit time
What does a straight diagonal line represent on a displacement-time graph?
Constant velocity
What does a flat, horizontal line represent on a displacement-time graph?
A stationary object - zero velocity
What does a curve (inwards) of increasing positive gradient represent on a displacement-time graph?
The object is accelerating
What does a curve (outwards) with decreasing positive gradient represent on a displacement-time graph?
An object decelerating
What does a flat, horizontal line on a velocity-time graph represent?
Constant velocity
What does a flat, horizontal line at y=0 on a velocity-time graph represent?
A stationary object
What does a flat, diagonal line represent on a velocity-time graphs?
Constant acceleration
What does a curve on a velocity-time graph represent?
Non-uniform acceleration
How do you work out displacement on a velocity-time graph?
Area under the graph
What is the suvat equation involving: a, t, u and v?
v = u + at
What is the suvat equation involving: u, s, t and v?
S = 1/2(v + u)t
What is the suvat equation involving: a, t, u and s?
S = ut + 1/2at^2
What is the suvat equation involving: a, t, s and v?
s = vt - 1/2at^2
What is the suvat equation involving: a, v, u and s?
v^2 = u^2 + 2as
What is acceleration due to free fall, g?
Acceleration of a body due to a gravitational field, with air resistance being ignored - 9.81 N/kg
Why do objects of different masses fall at the same rate?
Although the objects with different masses will have different magnitudes of gravitational forces acting on them, the proportion of forces to masses is the same which means the acceleration due to free fall is also the same.
What is thinking distance?
The distance the car travels between the driver seeing the hazard and applying the brakes.
What 5 factors affect thinking distance?
> Higher speed > Tiredness > Alcohol and drugs > Distractions > Age of driver
What is the braking distance?
The distance the car travels between applying the brakes to rest.
What 5 factors affect braking distance?
> Higher speed > Poor road conditions > Poor condition of brakes > Poor conditions of tyres > Mass of car (people/luggage)
How do you work out thinking distance?
Reaction time(s) x Speed of car(m/s)
What is the thinking distance and braking distance for a car at 20mph?
> T: 6m
> B: 6m
What is the thinking distance and braking distance for a car at 30mph?
> T: 9
> B: 14
What is the thinking distance and braking distance for a car at 40mph?
> T: 12m
> B: 24m
What is the thinking distance and braking distance for a car at 50mph?
> T: 15m
> B: 38m
What is the thinking distance and braking distance for a car at 60mph?
> T: 18m
> B: 55m
What is the thinking distance and braking distance for a car at 70mph?
> T: 21m
> B: 75m
What is one mile in m?
1609.3m
What is one mph in m/s?
1609.3 ÷ 3600 = 0.447m/s
