Make sure you are familiar with units for
Mass: kilogram (kg)
Distance: metre (m)
Speed: metre per second (m/s)
Acceleration: metre per second squared (m/s^2)
Force: newton (N)
Time: second (s)
Gravity: newton/kilogram (N/kg)
A distance time graph has distance on the y axis (usually in metres) and time on the x axis (usually in seconds). The gradient of the line (change in y/ change in x) is the speed. If the line is flat then the object is stationary.
To calculate average speed use
speed (m/s) = distance travelled (m)/ time taken (s)
Apparatus: stop watch and metre rule
mark the start and end positions for the know distance
use a metre rule to measure the distance
line up front of car with start point, release and start timer
move eyes to end point
stop timer when front of car passes end point
improve by repeating and averaging
make sure car starts from stationary
calculate average speed using : average speed = distance travelled/ time taken
on a velocity time graph the velocity-time graph the velocity is on the y axis (usually in m/s) and time is on the x axis (usually in s). If the line is flat then the object is moving at a constant velocity. the gradient of the line is the acceleration. The area under the line is the distance travelled.
Gradient = acceleration= change in y/ change in x = change in velocity/time
The area under the graph can be calculated as rectangles and triangles, or by counting boxes, is equal to the distance travelled.
v2=u2+2as
v= final speed
u= initial speed
a= acceleration
s= distance moved
see all the rearrangements of this equation.
Forces can act on a body to change the velocity, so the speed, direction or both.
Or forces can change the shape of a body, stretching it squishing it or twisting it.
scalars are quantities with only magnitude (size)
vectors are quantities with magnitude (size) and direction
Force has a magnitude measured in (N) but it also has a direction, a push or a pull, up, down, left or right. So force is a vector.
Stopping distance = Thinking distance + Breaking distance
Thinking distance Affected by:
Tiredness
Alcohol
speed of the car
Drugs (avoid as drugs can increase or decrease thinking distance)
Braking distance affected by:
Road conditions
Tyre conditions
Brake conditions
speed of the car
mass of the car
