SAT physics question -- Flag on a bicycle being ridden in the wind....

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SUMMARY

The discussion centers on a physics problem involving vector addition to determine the direction a flag on a bicycle will point when influenced by wind. A girl rides a bicycle at 15 miles per hour due north while a steady wind blows at 15 miles per hour from the east. The correct answer is that the flag will point toward the southwest (option C) due to the combined effects of the northward motion and the westward wind. Participants emphasized the importance of accurately interpreting wind direction and using free body diagrams (FBD) for clarity in vector representation.

PREREQUISITES
  • Understanding of vector addition
  • Knowledge of free body diagrams (FBD)
  • Familiarity with basic physics concepts of motion and forces
  • Ability to interpret directional components of vectors
NEXT STEPS
  • Study vector addition techniques in physics
  • Learn how to construct and analyze free body diagrams (FBD)
  • Explore the concept of apparent wind in moving systems
  • Review problems involving forces and motion in two dimensions
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Students studying physics, educators teaching vector concepts, and anyone interested in understanding the effects of wind on moving objects.

YMMMA
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Homework Statement


A girl is riding a bicycle at 15 miles per hour due north. A steady wind is blowing at 15 miles per hour from the east. A flag mounted on the bicycle will be stretched out toward the
(A) west (B) south (C) southwest (D) southeast (E) northeast

Homework Equations


Vector addition

The Attempt at a Solution


I drew an arrow pointing north then from its head i drew an arrow pointing east
I got E for the resultant vector. Is that right?
 
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YMMMA said:

Homework Statement


A girl is riding a bicycle at 15 miles per hour due north. A steady wind is blowing at 15 miles per hour from the east. A flag mounted on the bicycle will be stretched out toward the
(A) west (B) south (C) southwest (D) southeast (E) northeast

Homework Equations


Vector addition

The Attempt at a Solution


I drew an arrow pointing north then from its head i drew an arrow pointing east
I got E for the resultant vector. Is that right?
Welcome to the PF. :smile:

If the wind is "blowing from the east", the vector that represents it will not be pointing toward the east. Which way would it point?

Also, you should probably draw a free body diagram (FBD) of the flag to help you reason this problem out. Do you know how to do that? Show the forces of the two wind components on the flag...
 
Ahhhh, It says ‘from the east’ that means its directed west. Ugh, I should read well next time.
Thats how i draw the FBD. So, the answer is C.
 

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The correct answer is indeed C, but your vectors are still not quite right. You want the vectors to represent the wind forces on the flag. When the bike rider rides north, which was is the apparent wind blowing on the flag? :smile:
 
Oh, its west of south..
Do you mean the vector of the wind is from the tail of the north vector and directed west?
 
YMMMA said:
Oh, its west of south..
What's west of south?
YMMMA said:
Do you mean the vector of the wind is from the tail of the north vector and directed west?
I'm not sure what that means, sorry.

You have drawn the horizontal wind force vector correctly. Since the wind is coming from the east, the wind force from it is toward the west.

Since the bicycle is moving toward the north, the apparent wind force on the flag from that motion is pointing toward the ________
 
Sorry, I mean south of west.
I understood it. Now, I can imagine it pointing toward the south as a result of the motion.
Thanks a lot!
 
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