Speed at A
Timing will start when the signal at input 5:A changes and stops when the signal changes back.
Single interrupt card
Picket fence
When a picket fence is used to measure Speed at A, the measurements shown are for
instantaneous speed i.e. at this distance, the speed was.
This data can be used to plot a distance vs. time or instantaneous speed vs. time graph
To improve the accuracy of readings, an increment is automatically applied to a picket fence with a
pitch length of less than 60 mm. This will mean that there are fewer readings than number of pitches
on a fence.
Note:
It is envisaged that when a picket fence with a pitch length of 10 mm is used that it will be used on a buggy type investigations (which produce
slower times than dropping thorough light gates), the times are therefore averaged over less pitches.
Pitch length (
l) =
80 mm
- readings taken with a pitch increment of 1 (80 mm).
37
Pitch length (
l)
Readings taken with a pitch increment of
80 mm
1 (80 x 1 = 80 mm)
60 mm
1 (60 x 1 = 60 mm)
40 mm
2 (40 x 2 = 80 mm)
20 mm
4 (20 x 4 = 80 mm)
10 mm
5 (10 x 5 = 50 mm)
A
Stop A off Start A on
Use the blue buttons
to scroll through and
examine the readings
already taken
When a single interrupt card passes through a Light Gate,
the time measured is for how long the card took to pass
through the sensor.
Speed is calculated using the length of the interrupt card
divided by the time taken for the card to pass.
The blue buttons can be used to scroll through and examine
the readings already taken.
