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Far Horizon

An observer is on top of a lighthouse. How far from the foot of the lighthouse is the horizon that the observer can see?

Data Matching

Use your skill and judgement to match the sets of random data.

More or Less?

Are these estimates of physical quantities accurate?

Constantly Changing

Age 14 to 16 Challenge Level:
It is not envisaged that this problem would be used as a class problem.  It is more appropriate for an enthusiastic student or small group of students looking for a challenge to work on independently.