How Do They Calculate the 9 Degrees in the Force Diagram?

In summary, the conversation is about a homework problem that involves finding the angle and magnitude of a resultant force. The conversation discusses using inverse tangent to find the angle and finding the magnitude using components of the force. It also mentions the use of a calculator and the confusion of a 19N value. Ultimately, the correct magnitude of the force is determined to be sqrt(130^2+30^2).
  • #1
circuscircus
15
0

Homework Statement


http://img61.imageshack.us/img61/4585/8m1cdhx1.gif

I understood every except, How do they get the 9 degrees in part c?

Homework Equations





The Attempt at a Solution

 
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  • #2
Look at the components of the resultant of the three forces: using an inverse tangent you should be able to find the angle it makes with the x axis. (Draw a right triangle.)
 
  • #3
So then is arctan(30/190) 9 degrees?

(I don't have access to a radian calculator right now), also how do they get the 19N?
 
  • #4
circuscircus said:
So then is arctan(30/190) 9 degrees?
Yes.
(I don't have access to a radian calculator right now), also how do they get the 19N?
You don't need a radian calculator. (If ever you don't have a calculator handy, Google has one.)

The 19 N makes no sense. But the components are close enough, so you should be able to figure the magnitude properly from that.
 
  • #5
So the real F is sqrt(130^2+30^2) am I correct?
 
  • #6
circuscircus said:
So the real F is sqrt(130^2+30^2) am I correct?
Where did the 130 come from?
 

1. What is a force diagram?

A force diagram, also known as a free body diagram, is a visual representation of the forces acting on an object. It shows the direction and magnitude of each force, including external forces and reaction forces, and helps to analyze the motion of the object.

2. How do you draw a force diagram?

To draw a force diagram, start by identifying the object and all the forces acting on it. Then, draw a dot or a box to represent the object and use arrows to represent the direction and magnitude of each force. Make sure to label each force and use a scale to indicate the relative size of each force.

3. What are the different types of forces on a force diagram?

The different types of forces on a force diagram include contact forces (such as friction and tension), action-at-a-distance forces (such as gravity and electromagnetic forces), and reaction forces (such as normal force and support force).

4. How do you use a force diagram to solve a problem?

A force diagram can be used to solve a problem by providing a clear visual representation of all the forces acting on an object. By summing up all the forces in each direction, you can determine the net force and calculate the acceleration or motion of the object.

5. Are force diagrams only used in physics?

No, force diagrams are also used in other fields such as engineering and biomechanics. They are especially useful in analyzing the forces acting on complex systems, such as structures or human bodies, to better understand their motion and stability.

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