Free Body Diagram Help: Solving a System of Equations for Forces (PreCalc)

In summary, the conversation discusses solving a system of equations to find the values of B and C, representing different forces. The attempt at a solution involves using trigonometric functions and setting the sum of the forces in the x and y directions equal to zero. However, the weight of the crate is incorrectly stated as 500, leading to incorrect answers. After realizing the mistake, the correct values for B and C are found.
  • #1
Frankenstein19
56
0

Homework Statement


upload_2016-9-11_2-30-0.png


Homework Equations

The Attempt at a Solution


I got the components of each force. I called the Force from BA "B" and the force from CA "C" and then the force going downward on D "W"

FBy=sin30*B
FBx=-cos30*B

FCy=3/5*C
FCx=4/5*C

W=-500
~~~~~~
ΣFx= -B*cos30 + 4/5C = 0
ΣFy= B*sin30 + 3/5C - 500 = 0

-0.866*B +0.8C=0
0.5*B+0.6C=500

Now when I solve the system of equations by elimination I'm getting B=434 and C=470 (I even checked on a calculator) , but the back of the book says 478 for B and 518 for CWhat am I doing wrong?

I know this is kind of a dumb question like it's basic precalc but I've done it so many times over and over again I don't know what I am going wrong
 
Physics news on Phys.org
  • #2
You make a careless mistake with the weight of the crate. It is not 500, check again and you will get the correct answer =)
 
  • #3
honlin said:
You make a careless mistake with the weight of the crate. It is not 500, check again and you will get the correct answer =)
jvhgvhgvhgvhjsd TRUE <3 thank you
 

Related to Free Body Diagram Help: Solving a System of Equations for Forces (PreCalc)

1. What is a free body diagram?

A free body diagram is a visual representation of the forces acting on an object. It shows all the external forces acting on the object, such as gravity, normal force, friction, and applied forces.

2. Why is a free body diagram important?

A free body diagram helps to understand the forces acting on an object and how they affect its motion. It is an essential tool in physics and engineering for analyzing and solving problems involving forces.

3. How do I draw a free body diagram?

To draw a free body diagram, you first need to identify all the external forces acting on the object. Then, draw a simple sketch of the object and represent each force with an arrow pointing in the direction of the force. Label each force with its magnitude and direction.

4. What are the key components of a free body diagram?

A free body diagram includes a simple sketch of the object, labeled forces, and arrows representing the direction and magnitude of each force. It may also include labels for the object's mass and any angles involved.

5. Can a free body diagram be used for objects in motion?

Yes, a free body diagram can be used for objects in motion. It helps to analyze the forces that are causing the object to accelerate or decelerate. By drawing a free body diagram at different points in time, you can track changes in the forces and understand the object's motion.

Similar threads

  • Introductory Physics Homework Help
Replies
5
Views
587
  • Introductory Physics Homework Help
Replies
4
Views
1K
  • Introductory Physics Homework Help
Replies
9
Views
866
  • Introductory Physics Homework Help
Replies
3
Views
2K
  • Introductory Physics Homework Help
Replies
2
Views
1K
Replies
7
Views
1K
  • Introductory Physics Homework Help
Replies
13
Views
990
  • Introductory Physics Homework Help
Replies
12
Views
2K
  • Introductory Physics Homework Help
Replies
3
Views
2K
  • Introductory Physics Homework Help
Replies
34
Views
2K
Back
Top