How to Draw Force Diagrams for Suspended Objects and Equilibrium Situations

In summary: Thanks! Oh I get it. 40° should be across the 90° since it is supposed to be the angle the horizontal direction and T2 makes. Thanks!In summary, the rosary is suspended between two cables which are at an angle of 29ᴼ below horizontal. The mass of the rosary is 0.06 kg, and the vertical forces on the rosary are in equilibrium.
  • #1
santoki
34
0

Homework Statement



  1. An object with a mass of 300 kg is suspended between two cables which sag at an
    angle of 40ᴼ below horizontal, on either side. Draw a free-body diagram.
  2. While driving in your car, you notice that the string holding the rosary to your
    rear-view mirror makes an angle of θ = 29ᴼ with respect to the vertical. The mass of the
    rosary is 0.06 kg. Consider the vertical forces on the rosary to be in equilibrium
    during this situation.

2. The attempt at a solution

P3X7AaG.jpg
 
Physics news on Phys.org
  • #2
santoki said:

Homework Statement



  1. An object with a mass of 300 kg is suspended between two cables which sag at an
    angle of 40ᴼ below horizontal, on either side. Draw a free-body diagram.
  2. While driving in your car, you notice that the string holding the rosary to your
    rear-view mirror makes an angle of θ = 29ᴼ with respect to the vertical. The mass of the
    rosary is 0.06 kg. Consider the vertical forces on the rosary to be in equilibrium
    during this situation.

2. The attempt at a solution

P3X7AaG.jpg
1. You have drawn the cable tensions at an angle of 50° below horizontal. Can you give us the magnitudes of all three forces and make the length of the vectors proportional to these magnitudes?

2. What is the question? Is this supposed to be a free-body diagram for the rosary? Does it show that the net vertical force is 0? (ie. that the rosary is in vertical equilibrium?). If there is a net horizontal force what is causing it? Why do you have 30° as the angle?

AM
 
  • #3
Andrew Mason said:
1. You have drawn the cable tensions at an angle of 50° below horizontal. Can you give us the magnitudes of all three forces and make the length of the vectors proportional to these magnitudes?

2. What is the question? Is this supposed to be a free-body diagram for the rosary? Does it show that the net vertical force is 0? (ie. that the rosary is in vertical equilibrium?). If there is a net horizontal force what is causing it? Why do you have 30° as the angle?

AM

1. I will fix the lengths of the arrows according to their magnitude but does that mean the free-body diagram I have for #1 is correct?

2. I meant to write 30° in the question instead of 29°. I was just wondering if the free-body diagram I drew was correct. The diagram of the situation is below if it clears anything up:
xjk8P8A.png
 
  • #4
santoki said:
1. I will fix the lengths of the arrows according to their magnitude but does that mean the free-body diagram I have for #1 is correct?
The angles of the tension vectors are incorrect.

2. I meant to write 30° in the question instead of 29°. I was just wondering if the free-body diagram I drew was correct. The diagram of the situation is below if it clears anything up:
xjk8P8A.png
If the diagram is correct then the car and the rosary are accelerating sideways (which could mean it is turning a corner or that it just got t-boned by a truck). Provided you make the length of the tension vector the correct length, it appears to be correct.

AM
 
  • #5
Andrew Mason said:
The angles of the tension vectors are incorrect.

If the diagram is correct then the car and the rosary are accelerating sideways (which could mean it is turning a corner or that it just got t-boned by a truck). Provided you make the length of the tension vector the correct length, it appears to be correct.

AM


Would the #1 be correct if my tension vectors were pointing down since they are below the horizontal?
 
  • #6
santoki said:
Would the #1 be correct if my tension vectors were pointing down since they are below the horizontal?
The reference to an angle "below the horizontal" refers to the angle the cable makes with the horizontal direction. That angle is the angle between the cable and the horizontal. You are showing 40° as the angle between the cable and the vertical direction.

AM
 
  • #7
Andrew Mason said:
The reference to an angle "below the horizontal" refers to the angle the cable makes with the horizontal direction. That angle is the angle between the cable and the horizontal. You are showing 40° as the angle between the cable and the vertical direction.

AM

Oh I get it. 40° should be across the 90° since it is supposed to be the angle the horizontal direction and T2 makes.
 

1. How do I determine the direction of forces in a force diagram?

The direction of forces in a force diagram is determined by the direction in which the force is acting on the object. This can be determined by considering the position of the object and its surroundings, as well as any other known information about the forces acting on the object.

2. What is the purpose of a force diagram?

A force diagram is used to visually represent the forces acting on an object. It helps to simplify complex systems and understand the forces at play in a particular situation. This can be useful in analyzing the motion and behavior of objects.

3. How do I draw a force diagram for an object with multiple forces acting on it?

To draw a force diagram for an object with multiple forces, start by identifying all the forces acting on the object. Then, draw arrows representing each force with the length and direction corresponding to the magnitude and direction of the force. Make sure to label each force with its name and any known values, such as magnitude or direction.

4. Can a force diagram be used to calculate the net force on an object?

Yes, a force diagram can be used to calculate the net force on an object. To do this, add all the forces acting on the object in the same direction and subtract any forces acting in the opposite direction. The resulting value is the net force on the object.

5. Are there any common mistakes to avoid when drawing force diagrams?

One common mistake to avoid when drawing force diagrams is not considering all the forces acting on an object. It is important to identify and include all forces, even if they may seem small or insignificant. Another mistake is forgetting to label the forces or not accurately representing their direction and magnitude.

Similar threads

How to Draw a Force Diagram for an Object Suspended by Strings?
    • Introductory Physics Homework Help
Replies
2
Views
1K
Analyzing Forces & Electrons: Free Body Diagram
    • Introductory Physics Homework Help
Replies
2
Views
1K
Draw a diagram showing the forces acting on a plank and find x
    • Introductory Physics Homework Help
2
Replies
50
Views
5K
Mechanics: Explosion of an Object Vector Diagram
    • Introductory Physics Homework Help
2
Replies
38
Views
3K
Forces and Elevators: Free-Body Diagrams and Calculations
    • Introductory Physics Homework Help
Replies
9
Views
4K
Forces and Free-Body Diagrams in Real-World Scenarios
    • Introductory Physics Homework Help
Replies
5
Views
3K
Force diagram of a spinning mass tied to a string
    • Introductory Physics Homework Help
Replies
15
Views
3K
How Do You Calculate the Electric Charge on a Suspended Cork Ball?
    • Introductory Physics Homework Help
Replies
2
Views
2K
Resolving forces: Mass on a string
    • Introductory Physics Homework Help
Replies
4
Views
3K
B Torsion Involving an Off Axis Thrust
    • Classical Physics
2
Replies
47
Views
2K

Hot Threads

Recent Insights

Back
Top