Confusing static equilibrium problem

In summary, there was a problem involving a boy sitting on a ladder that rests on a frictionless floor. The ladder has a cross brace and an angle of 30 degrees at the apex. The question asked for the force exerted by the floor on each leg of the ladder and the tension in the cross brace. To solve for the force, the equation 4F = 900 was used since net Fy = 0. For the tension, trigonometry and Galileo's principle were suggested as helpful tools.
  • #1
barnsworth
5
0
static equilibrium problem

A 900-N boy sits on top of a ladder of negligible weight that rests on a frictionless floor as in http://m.domaindlx.com/barnsworth/physics.JPG. There is a cross brace halfway up the ladder, and the angle at the apex is 30 degrees.

a) What is the force exerted by floor on each leg of the ladder?

b) Find tension in the cross brace.

The first part was simple enough i guess. i did 4F = 900 since net Fy = 0, giving me F = 225 for (a).

Haven't the slightest clue on part (b) though. I don't know where to begin. :cry:

Anyways, thanks for any help in advance.
 
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  • #2
Hint: The floor exerts a normal force upwards, which creates a torque about the apex.
 
  • #3
Also, you can calculate the length of the cross Brace using trigoniometry...

then apply the nice hint of Galileo when calculating the torque...

regards
marlon
 

1. What is a confusing static equilibrium problem?

A confusing static equilibrium problem is a type of physics problem that involves finding the equilibrium state of a system where all forces acting on the system are balanced and the system is not moving. These types of problems can be challenging because they often involve multiple forces and complex systems.

2. How do I approach solving a confusing static equilibrium problem?

The best approach to solving a confusing static equilibrium problem is to first draw a free body diagram of the system, labeling all the known forces and their directions. Then, use the equations for equilibrium (sum of all forces in the x-direction and y-direction equals zero) to solve for any unknown forces. It may also be helpful to break the problem into smaller, simpler parts to make it more manageable.

3. What are some common mistakes people make when solving confusing static equilibrium problems?

Some common mistakes people make when solving confusing static equilibrium problems include not properly labeling forces and their directions, forgetting to include all forces acting on the system, and not breaking the problem into smaller, solvable parts. It is also important to use the correct equations and units when solving these types of problems.

4. How can I check my answer for a confusing static equilibrium problem?

To check your answer for a confusing static equilibrium problem, you can plug your values back into the equations for equilibrium and make sure they equal zero for both the x-direction and y-direction. You can also check if your answer makes logical sense, for example, if your calculated force is pulling the object in the opposite direction as the known force, then you may have made a mistake.

5. What are some real-life applications of confusing static equilibrium problems?

Confusing static equilibrium problems have many real-life applications, such as determining the stability of structures like bridges and buildings, analyzing the forces acting on a car during a turn or a rollercoaster during a loop, and understanding the balance of forces in the human body during activities like standing and walking. These types of problems help us understand and predict the behavior of objects and systems in our everyday lives.

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