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gregori [183]
4 years ago
9

A physics book is thrown horizontally at a velocity of 5.0 m/s from the top of a cliff 78.4 m high. How long does the book take

to reach the bottom of the cliff .
Physics
1 answer:
xenn [34]4 years ago
3 0

The book's vertical position in the air is

y=78.4\,\mathrm m-\dfrac12gt^2

where g=9.80\,\frac{\mathrm m}{\mathrm s}. It reaches the ground when y=0, at a time t such that

0=78.4\,\mathrm m-\dfrac12gt^2\implies t=4.00\,\mathrm s

So it takes the book 4 seconds to reach the bottom. The given initial velocity is irrelevant since it only has a horizontal component; vertically, the book is starting from rest.

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