One windless day you ride your bicycle at 25 km/h for one hour on a flat road. T
ID: 1438152 • Letter: O
Question
One windless day you ride your bicycle at 25 km/h for one hour on a flat road. The next day, you ride 5 km/h into a 20-km/h headwind for one hour on a flat road. Assuming that the force of the wind (the primary "friction" in this case) scales with the square of the relative velocity of the bike and wind, the wind's force is the same on both days. Which ride seemed to take more effort on your part? The ride on the windy day was harder. The ride on the windless day was harder. Both rides were about the same.Explanation / Answer
The answer is b, even if we ignore friction in the bike. Power is force times speed, so while the force is the same, the speed in b is much higher, so the power is much higher.
B) Windless day
Because Relative velocity on windless day is higher i.e 25 Kmph => F is proportional to 625
where as on windy day it is only 15kmph here F is proportional to 225 kmph
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