EXERCISE 29

 see solution motion: TOC for Knowledge Concepts, Exercises, and Solutions

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Let's revisit our Harley-Davidson in Exercise 26.  If I choose a cliff
that's 1200 meters above sea level (about the height of parts of the Grand
Canyon in Arizona), and push the Harley horizontally off the cliff:

(a) How fast would the Harley have to be going in order for it to
go into a stable orbit around Earth?
(b) How fast would the Harley have to be going in order for it to
escape Earth's gravity altogether and fly off into space?
(c) Let's say I fail to achieve either of these speeds, and thus
the Harley-Davidson falls to Earth,
1200 m below.  How much gravitational force is Earth exerting
on the Harley when it's one inch off the ground?  (Remember that
the Harley has a mass of 450 kg.)
(d) How does the amount of force compare to the amount of
force in Exercise 26, part (d)?  Does the motorcycle, upon
hitting the ground, suffer more, less, or equal damage here than
the situation in Exercise 26, where it falls 80 meters?