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Alina [70]
3 years ago
6

Hi! Can you help me? A rock is dropped off a tall building and takes 4 seconds to hit the ground. How fast was it going? Using y

our last answer, how tall was the building? Thanks! :)
Physics
1 answer:
AURORKA [14]3 years ago
4 0
<span><span>Free fall distance h=<span /></span></span>78.4532 m<span><span><span>
</span></span><span>Free fall velocity v=</span></span>39.2266 m/s<span><span><span>
</span></span><span>= </span></span>141.21576 km/h<span><span><span>
</span></span></span>
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Substituting,

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Now we can find the angular speed of the fan at the end of the 5th second, so after t = 5 s. It is given by:

\omega' = \omega_i + \alpha t

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Substituting,

\omega' = 0 + (45)(5)=225 rpm

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