A cannon ball is fired vertically upwards into the air. How fast
would it have to be fired to take 1 second to land?
How fast would it have to be fired to take 10, 100, 1,000 or
1,000,000 seconds to land?
What would be the highest point of the ball in each case?
(Assume that gravity is a constant
in your calculations)
Given that the radius of the earth is about 6000km, which of
your calculations would give a good approximation to reality?
At what speed would the approximation break down, in your
opinion?
Extension: why not try the
extension question Escape
From Planet Earth ?