Statics - Show a massless stick feels forces along the stick

In summary, a stick connected to other parts of a static system by hinges at its ends will experience forces at the hinges that are directed along the stick. However, if the stick has mass, the forces do not necessarily need to point along the stick. This can be demonstrated by considering a static system in which the forces do not point directly down the stick, yet still balance in order to prevent the stick from rotating or translating.
  • #1
MeMoses
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Homework Statement


A stick is connected to other partrs of a static system by hinges at its ends. Show that a massless stick feels forces, at the hinges, that are directed along the stick. Then show if the stick is massive, the forces do not need to point along the stick.


Homework Equations





The Attempt at a Solution


I have no idea where to start or how I can write this out to prove it in every situation. For instance its obvious the the stick attached to a wall and then a block, with a force point away from the wall, that all the forces go with the stick (exactly like tension in a massless rope). Then when mass is introduced the force of gravity clearly offsets the forces felt. I can use the later for the second part, but how does one go about showing the first part in all situations?
 
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  • #2
The key is that the system, including the stick, is static - i.e. the stick does not move.

So, draw a stick in space, and draw a couple of random force vectors at each end. What do the forces have to do for the stick to not move? It's not allowed to rotate or translate.

If the forces don't point directly down the stick, how can they balance?
 

1. How can a massless stick feel forces along its length?

A massless stick is an idealized object used in physics problems to simplify calculations. In reality, all objects have some mass, but for the purpose of analyzing forces and motion, the mass of the stick can be assumed to be zero. Therefore, the stick is able to transmit forces along its length without being affected by its own weight.

2. What types of forces can a massless stick experience?

A massless stick can experience different types of forces, such as tension, compression, and shear. These forces act along the length of the stick and can cause it to bend or break. However, because the stick is assumed to have no mass, it does not experience its own weight as a force.

3. Can a massless stick support weight?

Yes, a massless stick can support weight as long as the forces acting on it are balanced. For example, if an object is placed on one end of a massless stick, the stick will not break as long as an equal force is applied on the other end to counteract the weight of the object.

4. How does the length of a massless stick affect the forces it feels?

The length of a massless stick does not affect the forces it feels. This is because the stick is assumed to have no mass and therefore does not experience its own weight. The forces acting on the stick are determined by the external forces applied to it, not its length.

5. Can a massless stick be used in real life?

No, a massless stick is an idealized object used for theoretical purposes. In reality, all objects have some mass, no matter how small, and will experience weight and other forces. However, the concept of a massless stick can be useful in simplifying calculations and understanding the basics of statics and mechanics.

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