Circumference and arc length

There are 21 NRICH Mathematical resources connected to Circumference and arc length
Track design
problem

Track design

Age
14 to 16
Challenge level
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Where should runners start the 200m race so that they have all run the same distance by the finish?
Over The Pole
problem

Over The Pole

Age
16 to 18
Challenge level
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Two places are diametrically opposite each other on the same line of latitude. Compare the distances between them travelling along the line of latitude and travelling over the nearest pole.
Flight Path
problem

Flight Path

Age
16 to 18
Challenge level
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Use simple trigonometry to calculate the distance along the flight path from London to Sydney.
Rolling Inside
problem

Rolling Inside

Age
14 to 16
Challenge level
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Weekly Problem 11 - 2007
A circle of radius 1 rolls without slipping round the inside of a square of side length 4. Find an expression for the number of revolutions the circle makes.
Running Race
problem

Running Race

Age
14 to 16
Challenge level
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Weekly Problem 13 - 2006
If three runners run at the same constant speed around the race tracks, in which order do they finish?
Roll On
problem

Roll On

Age
14 to 16
Challenge level
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Weekly Problem 5 - 2006
How many times does the inside disc have to roll around the inside of the ring to return to its initial position?
Efficient cutting
problem

Efficient cutting

Age
11 to 14
Challenge level
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Use a single sheet of A4 paper and make a cylinder having the greatest possible volume. The cylinder must be closed off by a circle at each end.
Air Routes
problem

Air Routes

Age
16 to 18
Challenge level
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Find the distance of the shortest air route at an altitude of 6000 metres between London and Cape Town given the latitudes and longitudes. A simple application of scalar products of vectors.
Rollin' Rollin' Rollin'
problem

Rollin' Rollin' Rollin'

Age
11 to 14
Challenge level
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Two circles of equal radius touch at P. One circle is fixed whilst the other moves, rolling without slipping, all the way round. How many times does the moving coin revolve before returning to P?
Triangles and petals
problem

Triangles and petals

Age
14 to 16
Challenge level
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An equilateral triangle rotates around regular polygons and produces an outline like a flower. What are the perimeters of the different flowers?