GPS in Schools – Worksheet 2
Produced by the University of Tasmania in conjunction with Geoscience Australia as part of the AuScope GPS in Schools Project – 2014.
5
Measuring the distance covered after running for 5 minutes
Measuring the perimeter of a basketball court
Measuring the distance travelled down a highway in a car
Setting out a 100m running track
Measuring the length and width of a large paddock
12.
Compute the bearing of the track in Question 4 using the ‘Ruler’ tool. How does it compare to the bearing
you measured with a compass in Question 3? Is it larger or smaller than the compass bearing? Why?
Discrepancies between the GPS and compass bearings usually arise because compasses point towards
magnetic north, while the bearing/heading from Google Earth will be given in true north. The difference
between the true and magnetic bearings will vary across Australia. Other factors affecting the accuracy
of the bearings include compass accuracy (reading precision and/or magnetic interference) and GPS
accuracy.
13.
In Google Earth, load the track you saved from Question 8 and zoom in on it. Does the track accurately
portray the feature you mapped? Describe any differences and explain why they exist.
Some discrepancies are likely to exist between the feature on the imagery and what is mapped with the
GPS. This is usually due to GPS accuracy, but can also be caused by inaccurate coordinates on the
Google Earth imagery, or imagery that is old/inaccurate (e.g. mapping a shoreline at high tide vs. a
satellite image taken at low tide).
14.
In Google Earth, load the waypoints you saved from Part 7 and zoom in on them. Right click on each
waypoint and select ‘Properties’. Change the name and marker icon to something more appropriate, and
complete a detailed description for each feature that you’ve marked. Be sure to include details like name of
the feature, construction material, what it is used for, how many students it can accommodate etc. Make a
note your three waypoints below.
Waypoint 1: __________________________________________________
Waypoint 2: __________________________________________________
Waypoint 3: __________________________________________________
15.
How accurate are the positions of each waypoint compared to their actual location on the imagery? (Hint:
Use the ‘Ruler’ tool to determine their accuracy). What causes the difference between the actual location and
GPS location? You can adjust the position to the correct location in Google Earth when viewing the
‘Properties’ window for each waypoint by simply dragging the marker.
GPS accuracy is the major cause for differences between marked and actual waypoint locations.
