All Questions
117
questions
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2
answers
69
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Why isn't the moment always included in a free-body diagram?
Now I have seen many times both in my physics book and other books when drawing a free body diagram the moment is not included but the forces are. For example in 2d when a beam is fixed to a wall ...
- 103
0
votes
2
answers
71
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What determines the mechanical advantage of a lever?
This question is more specific than it seems. I am doing a mechanics-related project in class and we are learning about the functions of levers. Basically, I am confused as to what determines the ...
- 539
1
vote
1
answer
57
views
What is the amount of force applied on my back while I'm brushing teeth leaning forward?
This is a question I've had for several years but never had the knowledge to calculate myself. Please keep in mind I don't have much background in physics (learned some on middle school I guess...), ...
- 11
0
votes
2
answers
55
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Direction of the normal force [closed]
Suppose we have a bar with non-zero mass inside a hemispherical bucket fixed to the ground. Suppose, too, that there is friction between the bar and the inner spherical surface of the bucket. Part of ...
1
vote
3
answers
99
views
Sign of distance/arm when finding moment/torque
I know that $M=Fd$, but when I have a negative moment, does the sign of the moment matter when I'm calculating for distance? If yes, then what would it mean when distance is negative?
- 11
0
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answers
123
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Calculate weight distribution on 2D plane
I am trying to figure out how I can have a formula for the weight distribution on a square. But let me just describe what I am doing,
We have the classical horizontal beam support problem
And I we can ...
- 13
0
votes
0
answers
65
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2 rods connected at a pivot and attached to a spring
I have a question concerning this problem
First I calculate F1 by taking the origin at F2 and imposing equilibrium for the torque thus getting $ F_1 = \frac{a}{a+b} F $ and similarly for F2, then I ...
0
votes
1
answer
104
views
Is it possible to find the forces in this problem involving a block/beam/bar glued to the side of a wall?
This is a follow-up to a previous post of mine post. In that post, we concluded that a beam cannot be held in place by an application of normal forces in only one location if that location is off the ...
- 8,640
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1
answer
94
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Horizontal bar with one fixed end held by support beams touching/"pinching" it at one location to keep it from falling — Unsolvable problem?
Suppose we have a horizontal rigid bar held in place by two reinforcement beams (one above the bar and one below the bar), both of which are attached to a wall, such that they "clamp" the ...
- 8,640
20
votes
7
answers
5k
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Plank overhanging off a building — where does the normal force go?
Suppose there is a (uniform rectangular) plank of mass $m$ and total length $L$ that is on top of a building with some piece overhanging or jutting out past the building. Assume it isn't past the ...
- 8,640
0
votes
1
answer
93
views
What is the minimum vertical length of contact with the wall needed for an object to stay attached to a wall with an electrostatic force?
Say there's an object, a rectangular prism, that becomes electrically charged and then stuck on a wall using the electrostatic attraction between the object and the wall. The object and wall are ...
- 117
0
votes
2
answers
176
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Why does a beam balance restore? [duplicate]
This question was previously asked 11 years ago here, but I believe it does not answer my question for the following reasons:
(A) The first answer takes a different system, mine looks like this.
(B) ...
0
votes
1
answer
295
views
Minimum torque required to turn a large gear
I want to preface this by saying that this isn't homework, it's just a question I've made up myself (so it could just be impossible to solve), and I am a beginner so apologies if I miss something ...
- 15
1
vote
0
answers
69
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The force distribution along curved surface of contact [closed]
Is it possible to calculate the stress or contact force distribution over a curved contact surface?
I will try to explain the general idea in the figure below. Object $O$ (could be assumed to be rigid ...
- 11
0
votes
2
answers
63
views
Pure torque position
I understand that a pure torque does not have a point of application. Also, I can replace a pure torque with a force couple in opposite directions like a lug wrench.
However, force couple position ...
- 31