# All Questions

136,461 questions
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### Why is the force of gravity the net force?

The first image is the diagram** in this FBD, use Fg on m1 as its net force (not concerning the friction). why do you not subtract the tension force in Mass 1?
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### Planck's Constant is in units of Js does that mean photons are defined as 1 second of EM wave?

An EM wave delivers 6.626x10^-34 J per peak. This is true regardless of the EM wavelength. Each peak hits with the same energy, however the peaks are more tightly packed when the wavelengths are ...
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### What imparts the linear motion or the tangential velocity to natural satellites like the moon to enable them to be in orbit around the earth?

From Newton's laws of motion & gravitation, it is clear that the force of gravitation provides the necessary centripetal force which acts along the line joining the centre of masses of the earth &...
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### Electric Field for two identical charges

I have a task to find an electric field I don´t know how it should look like: We have 2 identical charges $q$ at a distance $d$, on x-axis at $(\frac{d}{2},0,0)$ and $(\frac{-d}{2},0,0)$. How can I ...
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### Kepler's 3rd law: ratios don't fit data

I have been looking at satellite orbits around the earth, or any object around any planet in fact, and am trying to find the orbital radius, or semi major length of a given satellite. Kepler's third ...
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### An rod is submerged into water in a graduated cylinder. Derive the total mass of the system as a function of depth of the rod [on hold]

I need help with this problem on a Buoyancy Lab. Consider an open graduated cylinder filled with 15 cm of water and is placed on the balance. A test rod is hung by a string and is partially ...
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### Hierarchy problems: calculating the mass of the Higgs vs. other SM particles

While reading up on hierarchy problems in particle physics (wikipedia), I stumbled onto the statement that in the Standard Model, there is no hierarchy problem (or at least it cannot be formulated) ...
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### Time Period of Oscillations ( A mechanical problem) [on hold]

So , basically I came across the following question : A massless rod (lying on a frictionless horizontal plane) is hinged at a point O. A string carrying a mass m at one end is attached to point A ...
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### Why does the Earth not fall towards the Sun? [duplicate]

According to http://wtamu.edu/~cbaird/sq/mobile/2013/07/01/why-doesnt-the-earth-fall-down/ , the earth does not fall down because of the gravitational force of the sun. At the same time , earth's ...
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### Interchanging $\epsilon_F$ and $\epsilon$ when deriving Density of States (DOS) of Free Electron Fermi Gas (FEFG)

When deriving the Density of States for a Free Electron Fermi Gas, Kittel seems to flamboyantly interchange $\epsilon$ and $\epsilon_F$ when going between equations. I am specifically puzzled as to ...
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### Substituting into quantum harmonic oscillator

I'm a bit confused by the substitution that is often performed with the harmonic oscillator. This step is usually skipped over, but it has me a bit confused. I attached a picture to show what is ...
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### Confusion regarding torque given by M×B

The magnetic torque acting on a loop of magnetic moment M placed in a magnetic field B, is given by τ=M×B. My question is, about which axis does this give the torque about? Is it the instantaneous ...
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### Does this graph represents only the magnitude of the friction force?

Friction force acts in the direction opposite to the relative motion between surfaces. For example, when a block is attempted to move from left to right with a force $F$, there will be an opposing ...
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### Confusion on conservation of energy in the beta decay process

In a question,regarding the beta decay process, it is given that. Assuming the anti-neutrino to be massless and possessing negligible energy and the neutron to be at rest, momentum and energy are ...