A 1 gram coin is which is initially at rest is dropped from the observation deck
ID: 1642378 • Letter: A
Question
A 1 gram coin is which is initially at rest is dropped from the observation deck of a skyscraper 300 meters above the street below. What is the work done by gravity on the coin as it falls? Joules Because there is air resistance the coin was slowed and hit the ground with a final velocity of 60 m/s. What is the kinetic energy of the coin at this speed?? Joules How much work was lost to air resistance as the coin fell? Joules Submit What is the average force exerted on the coin due to the air resistance as it fell? NewtonsExplanation / Answer
Work done by gravity = m g h
= (1 x 10^-3 kg) (9.8 m/s^2) (300 m)
= 2.94 J
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KE = m v^2 /2 = (1 x 10^-3) (60^2)/2
= 1.8 J
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KE when air resisatnce was absent,
KE = Work done by gravity =2.94 J
lost to resistance = 2.94 - 1.8 = 1.14 J
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W = f.d
- 1.14 = (f) (300) (cos180)
f = 3.8x 10^-3 N
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