P3a Flashcards
(12 cards)
What is the equation for distance?
Distance = average speed x time
How are units changed from km to m?
Times by 1000
Why does one type of speed camera take two photographs a certain time apart?
To confirm the distance travelled.
Why does one type of speed camera take two photographs when the vehicle moves over marked lines a known distance apart on the road?
To confirm the speed of the car.
How do average speed cameras work?
They use radar to detect when a car is speeding.
What is the relationship between speed, distance and time?
Increasing the speed, which increases the distance travelled in the same time.
Increasing the speed reduces the time needed to cover the same distance.
What equation do you use when an object is speeding up or slowing down and you need to find an average speed over the whole journey?
average speed = (u + v)/2
u= speed at the start v= speed at the end
How do you convert hours to seconds?
Times by 3600.
What do you need to know to interpret a distance - time graph?
Gradient = speed
Flat sections = where its stopped
Steeper the gradient, the faster it’s going
Downhill sections (negative gradient) mean it’s changed direction and is coming back towards it’s starting point.
Curves represent acceleration or deceleration.
Steepening curve means it’s speeding up (increasing gradient).
Levelling off curve means it’s slowing down.
How do you draw a distance - time graph?
If the independent variable is continuous (numerical data that can have any value within a range, e.g. length, volume, time) you should use a line graph to display the data?
1) Remember to include the units.
2) The dependant variable (the thing you measure) goes on the y-axis (the vertical one).
3) The independent variable (the thing you change) goes on the x - axis (the horizontal one).
4) When plotting points, use a sharp pencil and make a neat little cross.
5) Don’t join the dots up. Draw a line of best fit, or a curve if your points make a curve. When drawing a line or curve, try to draw the line through or as near to as many points as possible, ignoring anomalous results.
How do you interpret the gradient of a distance-time graph as speed (higher speed gives higher gradient).
Speed = gradient = vertical/horizontal
Don’t forget that you have to use the scale of the axes to work out the gradient. Don’t measure in cm. For example, m/s or km/h.
What is speed?
The distance travelled in a certain time .
