SP1 Motion Flashcards
What are vectors?
Quantities with magnitude and direction
What are scalars?
Quantities with magnitude only
Is force a vector or scalar?
Vector
Is velocity a vector or scalar?
Vector
Is displacement a vector or scalar?
Vector
Is weight a vector or scalar?
Vector
Is acceleration a vector or scalar?
Vector
Is momentum a vector or scalar?
Vector
Is speed a vector or scalar?
Scalar
Is distance a vector or scalar?
Scalar
Is mass a vector or scalar?
Scalar
Is energy a vector or scalar?
Scalar
Is temperature a vector or scalar?
Scalar
Is time a vector or scalar?
Scalar
Distance vs Displacement
Distance: how far an object has moved. Scalar quantity.
Displacement: the distance and direction in a straight line from an object’s start-finish point. Vector quantity.
What is your distance and displacement if you walk 5m north then 5m south?
Distance travelled = 10m
Displacement = 0m
Speed vs Velocity
Speed: how fast you are going e.g. 30mph. Scalar quantity.
Velocity: speed in a given direction e.g. 30mph north. Vector quantity.
Typical walking speed =
1.4 m/s
Typical running speed =
3m/s
Typical cycling speed =
5.5m/s
Typical speed of cars in a built up area =
13m/s
Typical speed of cars on a motorway =
31m/s
Typical speed of aeroplanes =
250m/s
Typical speed of trains =
55m/s
Typical speed of ferries =
15m/s
Typical wind speed =
5-20m/s
Typical speed of sound in air =
340m/s
Speed (m/s) =
s =
Distance (m) / Time (s)
d / t
Methods of measuring speed (by measuring distance and time):
- Stop watch and metre rule
best for distances less than 1m and times greates than 5s - Light gates
best option for short time intervals
get rid of human error caused by reaction times - Roling tape measure (the clicky wheel things)
use this + markers to measure and mark out distances
can be used to measure lartge distance and times
like walking speed - Video recording
see how far an object travels per frame
if you know how many frames per second the camera records you can find the distance travelled by the object in a given number of frames and the time it takes to do so
What is acceleration?
The rate of change of velocity
Acceleration (m/s²) =
a =
Change in velocity (m/s) / Time (s)
(v - u) / t
What is negative acceleration also called?
Deceleration
(if something slows down, the change in velocity is negative)
Acceleration due to gravity =
10m/s²
Formula for constant acceleration:
Final velocity² (m/s) - Initial velocity² (m/s) = 2 x Acceleration (m/s²) x Distance (m)
v² - u² = 2ax
On a Distance/Time graph, what does an uphill section represent?
Steady Speed
If it is steeper, it is going faster
On a Distance/Time graph, what does a flat line represent?
Stopped
On a Distance/Time graph, what does a curve getting steeper represent?
Acceleration
On a Distance/Time graph, what does a curve levelling off represent?
Deceleration
What does the gradient of a Distance/Time graph represent?
Speed
(because d/t = s)
Calculating the gradient (and thus speed) of a Distance/Time graph:
If the line is straight vs curved:
Straight:
speed = gradient = change in y/change in x = d/t
Curved:
Draw a tangent to the curve at the point you want to know, pick 2 points along the tangent, then do change in distance/change in time
On a Velocity/Time graph, what does an uphill section represent?
Constant acceleration
On a Velocity/Time graph, what does a flat line represent?
Steady Speed
On a Velocity/Time graph, what does an uphill curve represent?
Increasing acceleration
On a Velocity/Time graph, what does a downhill section represent?
Constant deceleration
What does the gradient of a Velocity/Time graph represent?
Acceleration
(Δv/t = a)
What does the area under the graph of a Velocity/Time graph represent?
Distance travelled
