Static equilibrium - girl on diving board

In summary, the problem involves a diving board of length L supported at a point x from the end, with a diver weighing w1 at the free end and the board itself weighing w2. The goal is to find the forces at the support point and the end that is held down. Using the moment and force equations, it is possible to express n2 in terms of w1 and w2 and n1 in terms of w1 and w2, but no further solution can be obtained due to the number of unknowns.
  • #1
smashd
10
1

Homework Statement


A diving board of length L is supported at a point a distance x from the end, and a diver weighing w1 stands at the free end (Figure 1) . The diving board is of uniform cross section and weighs w2.

MabwS9I.jpg

(Figure 1)​

  1. Find the force at the support point.
  2. Find the force at the end that is held down.

Homework Equations



[itex]\sum\tau_{z} = 0[/itex]

[itex]\sum F_{x} = 0[/itex]

[itex]\sum F_{y} = 0[/itex]

The Attempt at a Solution


So first I found the x & y components of the forces on the diving board. Oh, I also defined n2 as the normal force on the left end of the board, and n1 as the normal force at the support point. Up is positive and down is negative.

[itex]\sum F_{x} = 0[/itex]

[itex]\sum F_{y} = 0 = n_{1} - n_{2} - w_{1} - w_{2}[/itex]

Now to take the torque about an axis, since I have a lot of unknowns here. Here I've chosen the left normal force as the axis of rotation. Counter-clockwise is positive and clockwise is negative.

[itex]\sum\tau_{n_{2}} = 0 = n_{1}(L - x) - w_{2}(\frac{L}{2}) - w_{1}(L)[/itex]

Now I'm stuck and can't solve the two problems. I have a lot of unknowns and no other equations in my toolbox afaik. Help please!
 
Last edited:
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  • #2
Use the moment equation to find n2 in terms of w1 and w2. Then you can use the force equation to find n1 in terms of w1 and w2. That's all you can do with this problem.
 

1. How does static equilibrium apply to a girl standing on a diving board?

Static equilibrium refers to the state in which an object is at rest and all forces acting on it are balanced. In the case of a girl standing on a diving board, the forces acting on her are her weight and the reaction force from the diving board. When these forces are equal and opposite, the girl will be in static equilibrium and will not move.

2. What factors affect the static equilibrium of the girl on the diving board?

The static equilibrium of the girl on the diving board is affected by several factors, including her weight, the length and width of the diving board, and the distance of her center of mass from the end of the diving board. Additionally, external factors such as wind or movement of the diving board can also affect the static equilibrium.

3. How can you calculate the static equilibrium of the girl on the diving board?

To calculate the static equilibrium of the girl on the diving board, you will need to determine the weight of the girl and the reaction force from the diving board. The sum of these forces must be equal and opposite, and their respective moments (force x distance) must also be equal. By setting up and solving equations, you can determine the position of the girl on the diving board where she will be in static equilibrium.

4. What happens if the forces are not in static equilibrium?

If the forces on the girl on the diving board are not in static equilibrium, she will either start to move or the diving board will move. This could result in the girl falling off the diving board or the diving board tipping over. In order to prevent this, it is important to ensure that the forces are balanced and in static equilibrium.

5. How does the concept of static equilibrium apply to other objects?

Static equilibrium can be applied to any object that is at rest and has balanced forces acting on it. For example, a book sitting on a table, a car parked on a hill, or a flag hanging from a pole are all examples of static equilibrium. In each case, the weight of the object is balanced by an equal and opposite reaction force, resulting in a state of rest.

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