Activity for Olin Lathropâ€
| Type | On... | Excerpt | Status | Date |
|---|---|---|---|---|
| Edit | Post #292730 | Initial revision | — | about 2 months ago |
| Answer | — |
A: Why does tension change from 15 N to 17 N when forces are replaced by weights? Initially, if I apply forces of 20 N and 15 N directly at the ends of a massless string (without any pulley or masses), the tension in the string is exactly 15 N, as expected. No, it's not. You've got a problem without a solution, like dividing by 0. You can't apply 20 N to pull a string and the... (more) |
— | about 2 months ago |
| Comment | Post #292011 |
The hand-waving description is way too confusing. That really should be obvious. We don't know what is supporting the board, what orientation the dowel is at, which side of the board it is sticking out of, why there is any sheer load on the dowel, etc.
This question needs to be closed until fixe... (more) |
— | 4 months ago |
| Edit | Post #290045 | Initial revision | — | about 1 year ago |
| Answer | — |
A: Does an ultrasonic air humidifier use energy less energy than a steam humidifier? If you are already heating the space to maintain a constant temperature, and if both humidification methods result in the same eventual humidity, then the net energy used ends up the same. Any energy saving by a more efficient humidifier just makes the heating system work a little harder. Put anoth... (more) |
— | about 1 year ago |
| Edit | Post #289450 | Initial revision | — | over 1 year ago |
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A: How do I calculate which concentration of Vinegar is cheapest, before diluting it? Let w be the price of water that I'll use to dilute. Forget that. Unless you are in extraordinary circumstances, the price of water is so low compared to the vinegar as to be irrelevant. How do I deduce which concentration (of Vinegar) is cheapest to buy? Consider the price of only the vine... (more) |
— | over 1 year ago |
| Edit | Post #289076 | Initial revision | — | over 1 year ago |
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A: Are questions about Chemistry on topic? No, this site is about physics, not chemistry. Whether something is on topic anywhere else has no bearing on it being on topic here. That said, there are some gray areas between physics and chemistry that might be on topic. However, pure chemistry questions like "Why does baking soda fizz up whe... (more) |
— | over 1 year ago |
| Edit | Post #288245 | Initial revision | — | over 1 year ago |
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A: Why is it forbidden for two photons to turn into one? Think about how that is supposed to work. It seems you want two photons to somehow combine into a single photon and nothing else. That means the output photon must have the combined energy of the two input photons because you've provided no other place for the energy to go. And of course momentum ... (more) |
— | over 1 year ago |
| Comment | Post #287953 |
I can't make any sense of your question. The poor English, to the point of causing confusion, doesn't help. *Does every time a drop push toothpick back into bottle?* Drop from **where**? Your diagram shows no drops. So this toothpick can move? How is it held? The diagram shows the toothpick ove... (more) |
— | over 1 year ago |
| Edit | Post #287829 | Initial revision | — | almost 2 years ago |
| Answer | — |
A: To what extent does blender speed dissolve table salt + cold tap water? How do I deduce which setting suffices for mixing table salt + COLD tap water? Measure it. That really should have been obvious. My gut feel is that any reasonable agitation will work about equally well. The purpose of agitation is to prevent localized regions of highly saturated solution whe... (more) |
— | almost 2 years ago |
| Comment | Post #287068 |
The description is way too confusing to follow. Include a diagram, then we might have a chance to understand your setup. This question should be closed until then. Flagging for moderator attention. (more) |
— | about 2 years ago |
| Comment | Post #287039 |
C is a fixed point, so it can't be both at the center of the pool and on the surface of the water. The center is 1 m below the surface.
F1 is a force, but is specified in units of mass. Even assuming 1g gravity, you can't apply any significant force to the surface of the water (ignoring surface ... (more) |
— | about 2 years ago |
| Edit | Post #287019 |
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— | about 2 years ago |
| Edit | Post #287019 |
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— | about 2 years ago |
| Edit | Post #287019 | Initial revision | — | about 2 years ago |
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A: If you're stopped and about to be hit from behind, should you brake or release the brake? Basic answer It depends on what you care about. If you're primary concern is to minimize injury to the people in your car, then hold the brake firmly in ordinary low speed cases. This minimizes the motion of your car, which is what jerks around the passengers and causes injury. Actually the f... (more) |
— | about 2 years ago |
| Edit | Post #286936 |
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— | about 2 years ago |
| Edit | Post #286936 |
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— | about 2 years ago |
| Edit | Post #286936 | Initial revision | — | about 2 years ago |
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A: How exactly do eddy currents slow down objects moving though a magnetic field As the pendulum swings, it experiences a changing magnetic field from the externally fixed magnets. Any changing magnetic field causes eddy currents in a conductor. Since these conductors aren't perfect (the conductor has non-zero resistivity), energy will be dissipated by eddy currents. That ener... (more) |
— | about 2 years ago |
| Comment | Post #286906 |
Shouldn't that be "-" in first equation? (more) |
— | over 2 years ago |
| Comment | Post #286898 |
In addition, your "measurement value" is really hard to parse, to the point of being rude. -1 for the sloppiness. (more) |
— | over 2 years ago |
| Edit | Post #286873 | Initial revision | — | over 2 years ago |
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A: System of ODEs models in physics Pretty much any system where the state of one thing effects the rate of another, and the state of that other thing effects the rate of the first. Surely you can think of a few of those. One example is a capacitor and inductor wired in parallel. The voltage on the cap effects the rate of current ... (more) |
— | over 2 years ago |
| Comment | Post #286842 |
All charges are equal, so "sorting" them doesn't make any sense. Sort by what criteria? (more) |
— | over 2 years ago |
| Edit | Post #286811 |
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— | over 2 years ago |
| Edit | Post #286811 | Initial revision | — | over 2 years ago |
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A: Calculate inductance using laws of electromagnetism Can we use other laws of electromagnetism to calculate the inductance of a piece of wire just like we used Gauss's law to calculate the capacitance of the 2 seperated conductors? Yes. The inductance of a length of wire is a function of the diameter of that wire and the material around it. (more) |
— | over 2 years ago |
| Edit | Post #286667 | Initial revision | — | over 2 years ago |
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A: Why can these Single Vision lenses slow myopia for kids, but not adults? Why can these Single Vision lenses slow myopia for kids, but not adults? Kids' eyeballs are still growing, so there is opportunity to steer them into growing to a less myopic final result. (more) |
— | over 2 years ago |
| Edit | Post #286666 | Initial revision | — | over 2 years ago |
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A: What should this community's policy on "explain like I'm five" and similar statements be? This site is not for five year olds. We are not kindergarten teachers. Asking a bunch of volunteers on the internet to explain physics to a five year old is a waste of time. Explanations at that level are out there and widely available. Imagine if we actually did answer appropriately for a fi... (more) |
— | over 2 years ago |
| Edit | Post #286646 |
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— | over 2 years ago |
| Edit | Post #286646 | Initial revision | — | over 2 years ago |
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A: Optically, why are circular eyeglasses lenses better than rectangular? All refractive lenses are approximations of the ideal. This is particularly the case of single-element lenses such as in eyeglasses. It so happens that the centers of such lenses are closer approximations to the ideal than points further from the center. Put another way, it's easier to make good... (more) |
— | over 2 years ago |
| Comment | Post #286404 |
Canina already mentioned the speeds, but also consider how long it would take to get to those speeds. To prevent squishing your cosmonaut, you probably want to keep long term acceleration to 1 g. At that rate, it takes about 6 months just to get to ½c, at which time dilation is still very sm... (more) |
— | over 2 years ago |
| Edit | Post #286316 | Initial revision | — | over 2 years ago |
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A: Why can someone observe light, even when the light fails to illume that someone? The light shines on everything in an unblocked direct line from the light source. This light is quite bright, so can be seen by human eyes all the way out to the horizon (until the curvature of the earth ends up blocking the direct line). It seems you are confused about the amount of light needed... (more) |
— | over 2 years ago |
| Edit | Post #286315 | Initial revision | — | over 2 years ago |
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A: Why do markers reflect light, even when the light source fails to illumine the space between the source and markers? It counters intuition that although a light fails to illumine the area between the source and the target, the light can still illumine SOLELY the target! The light is illuminating everything. The photons don't magically disintegrate some fixed distance from the light source. The illumination get... (more) |
— | over 2 years ago |
| Comment | Post #285323 |
-1 for the many undefined variables. Ping me when fixed and I'll undo the downvote. (more) |
— | over 2 years ago |
| Comment | Post #285193 |
You have posted a lot of questions here without defining what your variables mean. The E=mc<sup>2</sup> equation is well known enough that most people probably understand that E is energy, m is mass, and c is the speed of light. However, you don't define terms in more obscure equations either. Wha... (more) |
— | almost 3 years ago |
| Edit | Post #285862 | Initial revision | — | almost 3 years ago |
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A: Calculating Surface temperatures of a thermal insulator The "R value" of insulation is its thermal resistance. It tells you how much of a temperature difference is required to transfer a certain amount of heat power per unit area. The R-value you see on insulation in stores, at least here in North America, is in some arcane units, like °F per BTU pe... (more) |
— | almost 3 years ago |
| Edit | Post #285704 | Initial revision | — | almost 3 years ago |
| Answer | — |
A: Conductivity with angle of light We don't know the details of your setup, but most likely there was a partially reflective surface over the actual photoresistor. The photoresistor itself may also be partially reflective. A higher fraction of the light is reflected off such surfaces at low angles. That means less of the light is... (more) |
— | almost 3 years ago |