# Questions tagged [statics]

Statics is branch of engineering concerned with the analysis of forces and moments on physical systems in static equilibrium.

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### Why is the truss member between two fixed supports zero?

If i first assume the member(far left) to not be zero and use method of joint at both points of constraint, with both constraints having unknown vertical reaction, it cannot be solved. Load and ...
7k views

### How to find reaction forces in trusses?

I'm stucked at trying to find the vertical reaction at top and bottom constraint, i know how to do the rest. Can you show me how?
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### cut section method in truss

For moment about D , how could the FGF sin26.6 generate moment about D ? FGF sin26.6 is located above point D , right ? How could FGF sin26.6 generate moment about D ?
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### Draw the FBD of the entire frame, assuming that friction and the weights of the members are negligible. How many unknowns appear on this FBD?

Draw the FBD of the entire frame, assuming that friction and the weights of the members are negligible. How many unknowns appear on this FBD? This is what I've tried so far. I have four unknowns. ...
623 views

### Drawing conclusions about 3d truss from 2d model

I am on the task of analysing the load capacity of a warren-ish truss bridge similar to this one. I do not, however, have the software or skill to model and analyse a 3D structure. I was wondering ...
117 views

### Finding downward force of lever bar

I am working on a DIY project, I am trying to replicate a bar compressor which for some reason is only sold in Europe so I thought it would be fun to make my own without having to waste so much ...
59 views

### Deformation of a fixed-fixed beam with perfectly plastic yield stresses

Here's the setup: The problem asks to find the relationship between the force $P$ and the displacement of B ($u_B$). I have done this correctly: P = \left(\dfrac{E_1A_1}{L_1}+\dfrac{E_2A_2}{L_2}\...
5k views

### How does a pulley (with friction) satisfy equilibrium?

In the picture shown : Suppose that there is a man applying a force $F$ in order to support the box using a cord that wraps over a frictionless pulley (the system is in equilibrium and nothing is ...
4k views

### Why do we ignore horizontal reactions at roller supports?

When talking about roller supports in a statics problem, we say that the roller prevents only the vertical translation of the beam, but not the rotation or the horizontal translation of it. So there ...
157 views

### Equilibrium of a Rod with an Actuator

I'm an EE student by trade, but I've started a project that requires some mechanical analysis, and I've run up against a bit of a wall in my calculations. The system in question that I'm looking at ...
204 views

### Why does a simple pin-ended triangular (arched/curved) beam deflect more due to secondary effects (non-linear analysis)?

I cannot wrap my head around this. I have made two simple models, a triangular (or curved or arched) beam that is pin ended and has a single point load of 1N downwards at it's center, and a flat beam ...
2k views

### Calculating the moments due to reaction forces on a bent beam

I am trying to solve the following problem: EXAMPLE 2.10 Determine the reactions on the beam in Fig. 2–30a. Assume $B$ is a pin and the support at $B$ is a roller (smooth surface). ...
3k views

### How should I position two shelf supports for the best distribution of load?

I'd like to mount a shelf on the wall. I have two shelf supports to do so, like this: Relative to the shelf, where do I place the (blue) supports to achieve the best distribution of load?
199 views

### Why is the moment of forces on a rigid body in static equilibrium must be zero about any point, even if the position of that point is not on the body

Why is it necessary for the moment of the forces on a rigid body in static equilibrium to be zero about any point, even if the position of that point is not on the body itself.
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### Where did I go wrong conceptually when attempting to calculate the maximum force on a truss at a given joint?

In the problem statement below, the question states to find the maximum load $\vec{P}$ that the truss can support. My method of approach was: Draw a FBD for the entire structure. Generally I would ...
470 views

### Differential equation of the vertical displacement of a cable

Given a cable (totally flexible) fixed at both ends, subjected to a vertical force $f(x)$ in his plane, with variable area $A(x)$, and variable elasticity $E(x)$ I want to find the differential ...
949 views

### Maximum deflection of a beam with both ends fixed and distributed load

I'm designing a part, and I'm trying to figure out what distance a slot should be from the bottom of the part. For simplicity in analysis, I'm approximating the region between the bottom of the slot ...
4k views

### Horizontal and vertical forces on supports

Calculate the horizontal and vertical components of the reactions at the supports. I found the horizontal force for the pin by adding the forces to 0 and I know I can find the vertical reaction of ...
189 views

I am not yet at the chapter of equations of equilibrium, plus it says the couple moment is not 0, so I assume it just about the loadings and not including the reactive forces and reactive moment. So ...
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This is the question, but with me 6 kN/m is 4 kN/m and 2 kN/m is 2.5 kN/m. And the length is not 4 but 9 metres. I am not yet at the chapter of equations of equilibrium, plus it says the couple ...
Here is the exercise that I just can't seem to figure out. The answer should be 71.9 Nm with coordinate angles 44.2, 131 and 103. I know that the couple moments caused by the forces $F_1$, $F_2$, and ...