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December 19, 2014

December 19, 2014

Posted by **qwertzuiop** on Saturday, January 28, 2012 at 7:56pm.

And, for how much time was Marie's arrow in the air?

- physics -
**Damon**, Saturday, January 28, 2012 at 8:36pmv = Vi - 9.8 t

0 = Vi - 9.8 t

Vi = 9.8 t

99.5 = Vi t -4.9 t^2

99.5 = 9.8 t^2 - 4.9 t^2 = 4.9 t^2

t = 4.5 seconds to top

so

Vi = 9.8 * 4.5 = 44.2 m/s

You could also do this by conservation of energy

(1/2) m Vi^2 = m g h

so

Vi = sqrt (2*9.8*99.5)

= 44.2 m/s

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