Statics Question: Finding resultant force and orientation

Click For Summary
The discussion focuses on calculating the resultant force and its direction based on given forces F1 and F2. The magnitude of the resultant force was correctly determined to be 402 lb. However, there is confusion regarding the calculation of the direction, with an initial angle of 71.6 degrees being misapplied. The correct approach involves finding the components of both forces and then determining the angle relative to the positive x-axis. Clarification is sought on whether to subtract from 360 degrees or adjust the angle differently to express it counterclockwise.
Chandasouk
Messages
163
Reaction score
0
Hibbler.ch2.p1.jpg


Determine the magnitude of the resultant force FR. Assume that F1 = 230 and F2 = 395
Express your answer to three significant figures and include the appropriate units.

Determine the direction of the resultant force FR , measured counterclockwise from the positive x axis.


I got the magnitude as 402lb which is correct, but I am having trouble finding the direction of the force.

I have the following work below

http://img5.imageshack.us/img5/1954/resultantforce.png

So I get \phi=71.6 degrees

Now the first quadrant has an angle from F1 to the x-axis that measures at 60 degrees. What I did was 71.6-60 degrees = 11.6 degrees and said that was the angle of the resultant force, but this answer is wrong.

Can anyone explain how to find the angle? Should I be subtracting 360 from 11.6 degrees instead since it wants the position counterclockwise?
 
Last edited by a moderator:
Physics news on Phys.org
Why don't you find the components of F1 and F2 and add them to determine the resultant?
 
The book claims the answer is that all the magnitudes are the same because "the gravitational force on the penguin is the same". I'm having trouble understanding this. I thought the buoyant force was equal to the weight of the fluid displaced. Weight depends on mass which depends on density. Therefore, due to the differing densities the buoyant force will be different in each case? Is this incorrect?

Similar threads

  • · Replies 18 ·
Replies
18
Views
2K
  • · Replies 5 ·
Replies
5
Views
3K
  • · Replies 8 ·
Replies
8
Views
2K
  • · Replies 1 ·
Replies
1
Views
2K
  • · Replies 5 ·
Replies
5
Views
3K
Replies
5
Views
1K
Replies
4
Views
3K
  • · Replies 3 ·
Replies
3
Views
3K
Replies
4
Views
2K
  • · Replies 6 ·
Replies
6
Views
3K