Mathematics Stack Exchange
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Questions tagged [physics]

Questions on the mathematics required to solve problems in physics. For questions from the field of mathematical physics use (mathematical-physics) tag instead.

This tag is for questions on the mathematics required to solve problems in physics and should not be confused with those on physics concepts. Pure physics questions should go in the Physics Stack Exchange. For questions in the field of mathematical physics, please use the tag instead.

5951 questions
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Canceling out a term

Trying to do a physics problem but I can't understand the mathematical logic on why the term m cancels out completely in this equation: $\frac{1}{2}mv_0^2=\frac{1}{2}mv_1^2+mg\cdot 2r$ I understand canceling the first terms where m is multiplied my…
bontu
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The solution of Schrodinger equation in an infinite wall with step potential???

Click Here for Image!!! I want to ask how to deal with the equation on $L/2 < x < L$ region. The equation has a general form $C e^{-k_2 L/2} + D e^{k_2 L/2}$ on $L/2 < x < L$. However, as there exists infinite barrier at $x = L$, we do have non-zero…
gabriel
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Baseball distance throwing problem

I am trying to come up with a formula that estimates the speed of a baseball given the total distance you throw the ball. I know the maximum angle to optimize distance in the x direction is 45 degrees. I am looking for something that includes the…
Calvin Cacciamani
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Calculate the moment of inertia of a disk of radius $R$ with a hole of radius $r$ and center a distance $d$ from the original disk.

I calculated the inertia using $I_{\rm tot}= I_d+I_h$ where $I_{tot}$ is the inertia of the disk without a hole $\left(\frac12 MR^2\right)$ in reference to its center of mass (origin), $I_d$ is the inertia of the disk with a hole (what we solve…
shvd
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Are massless objects immovable?

I didn't think so, but I'm looking at a course problem, A string of length $L$ and line density $\rho$ is under a tension $\rho c^2$. Its transverse displacement is $y(x,t)$. The string is fastened to rings at $x=0$ and $x=L$. The masses of…
mjc
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How to calculate the work done by water on a diver?

Background Consider the a person with a mass of $m = 65 \text {kg}$ falling into water with a valocity of $14.007 \frac ms$. At a depth of $3.1m$ the diver comes to a stop. Question How large is the force applied to the diver by the water? By this,…
Alec
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Exercise about defining "same level" in Conceptual Mathematics

Near the start of Lawvere and Schanuel's Conceptual Mathematics they ask: The part of Galileo’s work which we discussed is really concerned with only a small portion of space, say the immediate neighbourhood of the tower of Pisa. Since the ground…
Robin Adams
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the centroid of a plane area - how to interpret 1/2 in the summation formula for Mx?

Please explain why "1/2" appears in the following summation. My understanding is that Mx = y*(dA), so I'm looking for an interpretation of the 1/2 factor there especially, as for y=f(x) and A=f(x)*dx it seems logical to have f(x) squared, but what…
user551034
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Calculating the acceleration of an object on the end of a lever.

I have a lever that is 16 feat long and pivots on a fixed point 4 ft from the left/heavy end, and 12ft from the right/light end. I wanted to calculate the acceleration of the right end due to gravity. The right end ways 10 lbs. The left end…
csga5000
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characterization of potential

I have a Field $F(x,y):= \left( \begin{array}{c} ay\\ 0\\ \end{array} \right)$ and I have to find out whether this field is potential. Well despite the terminology( wich is not completely clear to me) i thought that the answer is affermative iff…
sigmatau
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What initial velocity is required for a bullet to enter orbit?

I need some help for a school assignment. I'm trying to make a differential equation to solve in Comsol. The part I'm having trouble with is the fact that air resistance and gravity changes based on the bullets vertical position. I have absolutely…
grötorm
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Question on angular acceleration in OCR A Level further maths textbook

OCR A Level Further maths: mechanics, Year $1.$ Chapter $4$ Section $2$: Acceleration in horizontal circular motion. $\omega$ is angular speed and is defined as $\frac{d\theta}{d t},$ sometimes written as $\overset{.}{\theta}.$ An equation for…
Adam Rubinson
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Question about initial speed in kinematic equation

I am looking at this question: A stone is dropped into a river from a bridge 43.9 ill above the water. Another stone is thrown vertically down 1.00 s after the first is dropped. The stones strike the water at the same time. (a) What is the initial…
user130306
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Time of flight of a javelin

An athlete throws a javelin at an angle of $45^{\circ}$ to the horizontal and, after a time interval $t$, the javelin hits the ground $16$ $\text{m}$ in front of the throwing point . Neglecting the air resistance and the athlete's height, the time…
Lambert macuse
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How do I calculate the BRDF (Bidirectional Reflectance Distribution Function)?

I've been attempting to calculate the BRDF to use in the second pass of a Photon Mapping program. Below is the definition of BRDF according to Wikipedia. $$ f_{r}(w_{i},w_{r}) = \frac{dL_{r}(w_{r})}{dE_{i}(w_{i})} $$ I've managed to calculate the…
Alex Hira
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