What is the Work Done by Air Resistance on a Round Trip?

AI Thread Summary
The discussion revolves around calculating the work done by air resistance during a bicyclist's round trip of 1.32 km in each direction, facing a resistive force of 6.12 N. Initial calculations yielded -16.14 J, which was incorrect. Participants suggested converting the distance from kilometers to meters and considering the net force as potential factors for the error. Ultimately, converting the distance resolved the issue, leading to the correct answer. The importance of unit conversion in physics problems is emphasized.
emerica1254
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Homework Statement



A bicyclist rides 1.32 km due east, while the resistive force from the air has a magnitude of 6.12 N and points due west. The rider then turns around and rides 1.32 km due west, back to her starting point. The resistive force from the air on the return trip has a magnitude of 6.12 N and points due east. Find the work done by the resistive force during the round trip

Homework Equations



W=(fcosΘ)s

The Attempt at a Solution


6.12*cos180*1.32+6.12*cos180*1.32= -16.14, but this is not the right answer
 
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hi emerica1254! :smile:
emerica1254 said:
6.12*cos180*1.32+6.12*cos180*1.32= -16.14, but this is not the right answer

looks right to me :confused:

have you tried -16.1 J ?
 
tiny-tim said:
hi emerica1254! :smile:


looks right to me :confused:

have you tried -16.1 J ?

Still didn't work and i have only one more chance to get it right, so if anyone else knows what I'm doing wrong i would appreciate it
 
Well, there's two possible things I see.

1) The problem states that the distance is 1.32 km. You should convert this to meters.

2) Or, possibly, they are looking for net force. In which case, as a vector sum, -8078 in one direction plus +8078 in the opposite direction would equal zero.

I'm thinking they really want it done the first way, though.
 
p21bass said:
Well, there's two possible things I see.

1) The problem states that the distance is 1.32 km. You should convert this to meters.

2) Or, possibly, they are looking for net force. In which case, as a vector sum, -8078 in one direction plus +8078 in the opposite direction would equal zero.

I'm thinking they really want it done the first way, though.

Converting to m worked thanks for all your help.
 
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