# All Questions

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### How far should I fill up a water bottle to make it the most resilient to accidental bumping? [closed]

I came across a situation similar to the one in the picture shown below, where you have a water bottle that is being knocked over by accident. Naturally, I wondered how much I would have to fill a ...
45 views

### Pressure of rubber band on cylinder taking friction into account

Suppose I have stretched a rubber band around a cylinder of radius $R$ such that the rubber band is under tension $T$. My understanding is that in the ideal situation, with no friction, the band ...
81 views

### Magnitude of F about line CD (Mechanics, 3D vector system)

I am having trouble with this question: I will write out the question below to make it easier for other people googling the question to find it: 2/139 If the magnitude of the moment of F about line ...
70 views

### How does beam pinned at one end resist moment?

This beam is constrained by a pin at one end, so it is free to rotate around that point. If a moment M is applied, the beam cannot move since any rotation would involve motion of the COM, which is not ...
272 views

### Conditions for Static Equilibrium of Rigid Body [duplicate]

When there are forces acting on a rigid body, the two conditions that has to be satisfied for the body to be in static equilibrium are: 1. The sum of all forces must be zero (translational equilibirum)...
105 views

### Statics: What it means if a rope snaps

There is a drawbridge that is held up by a hinge attached to a vertical wall on one side, and by a vertical rope on the other side. Say a horse starts walking from the wall towards the rope and at a ...
98 views

### Express $\tan{\theta}$ in terms of $\alpha$ and $\mu_s$ [closed]

Problem: Determine the least angle $\theta$ where equilibrium is possible. Express $\tan{\theta}$ in terms of $\alpha$ and $\mu_s$ Attempt: I started of with drawing out all the acting forces: ...
204 views

### Membrane shape under pressure

If I have a circular membrane that is fixed by the edges and then I apply a uniform pressure to the membrane (let's say the membrane is the top of a circular chamber that has a rigid wall and flat ...
420 views

### Distribution of normal force on a book resting on the edge of a table

Assume a uniform book is resting on a table. The book has length $1$. But not the entire book is resting on the table, a bit $\alpha$ is sticking out of the table. Obviously, due to experience, we ...
801 views

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### Optimal placement of support joist under shelf

Assume an ideal board, supported by two joists. Where should those two joists be optimally placed? Instinctively, I'd say at somewhat less than 25% and somewhat more than 75% of the extend of the ...
3k views

### Direction of tension?

If you draw the free body diagram of the frame above, what direction would the tension force acting on the frame be - to the right or down? Because the rope it horizontal at some points but vertical ...
144 views

### Can all systems be put in equilibrium?

I'm in a first year statics course. We have spent the whole semester solving for forces and moments so that the system is in equilibrium. When we are given a system, we immediately begin solving for ...
1k views

### Why don't couple forces violate Newton's First Law?

If you have some random object at rest and you apply a couple to it, the net force acting on it is zero. However because a moment acts on it, it starts to rotate. So you had an object at rest, a net ...
495 views

### Why does moment equilibrium at one point of an object mean the moment is at equilibrium for the whole system?

In class my prof said that when showing a system is at equilibrium it suffices to show that the moment at one point is zero. Why? Why does showing the moment at a point is zero imply the moment of the ...
2k views

### Why is moment dependent on the distance from the point of rotation to the force?

The formula for moment is: $$M = Fd$$ Where F is the force applied on the object and d is the perpendicular distance from the point of rotation to the line of action of the force. Why? Intuitively, ...
443 views

### Is it possible to deduce the Archimedes' law of the lever using only the laws of conservation of the physics?

Is it possible to deduce the Archimedes' law of the lever using only the laws of conservation of the classical mechanics? I never saw (which is strange), but I think that it's possible.
1k views

### Equilibrium of Force Systems including Torque

please help me to solve this problem.. this is only the #3 on my homework and the only thing i didn't know here is how to calculate the tension T. please teach me how to solve the tension here ...
2k views

### Why are some jenga pieces easier to remove than others?

Jenga is a game place with wooden blocks stacked on top of one another in an alternating pattern. Players take turns removing blocks from any layer and placing them on top. As the game progresses ...
1k views

### Statics of Rigid Bodies — Can there be two possible solutions?

I've been working on a question and there seem to be two possible solutions. My own solution does not match the one given in the book. However, after resolving forces and taking moments with both ...
505 views

### Bowling ball on a rubber sheet

After reading a layman's guide to general relativity, I began to wonder what shape a bowling ball on a large rubber sheet would produce. For simplicity, I would like to assume that Hooke's law applies ...
210 views

### Obtaining point of application of Ground Reaction Force with use of a hyperstatic load-cell array platform

I'm looking for the theory of an experiment that is giving me a hard time to perform. I have an instrument composed of a rigid horizontal square plate rigidly supported under each corner by a load-...
4k views

### Forces and torques about the CENTER OF MASS of a physical pendulum

I'm currently stumped by the following situation. Say we've got a rectangular physical pendulum (think ruler with a hole-punch at one end). It's trivial to analyze the motion of the pendulum with the ...
22k views

### Calculation of the maximum load to the bar

Looking for a way of calculating the maximum weight (W) to the rod with the given length (L) where the rod did not break and that only bend for (b) mm. Need only approximative solution (read: simple ...
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### Formula for implementing a simulated weighing scale

Background: I'm on the pledge drive committee for a non-profit group, and there is an issue that is always contentious within this group; thankfully the group is amicable, although competitive, about ...