mathematics teaching 10 ~ 16
Wednesday, 16 March 2011
how far away is the horizon?
when you stand on a beach, with your toes in the sea, how far away is the horizon?
it looks further away than it is because light gets bent
worth asking students to guess first
it is surprisingly close
an exaggerated diagram shows that this is a simple enough application of the pythagoras rule
since the Earth isn't spherical use the average radius: 6371km
for a 2m (0.002km) eye height the distance is a mere 5.1 km (3 miles)
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