Mathematics Stack Exchange
Mathematics Stack Exchange

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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If your journey lasts 11 hours and 15 minutes what speed are you travelling at if you cover 90 miles?

I'm at a really loose end - I just can't seem to grab some fundamentals of Speed Distance Time. Can someone explain to me how they discover the answer to the following equipped with steps on how to figure out. I really cannot remember the process in…
karlb123
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Half-life equations

The half-life of radon-$222$ is $3.8$ days. if a sample contains $4.2$ grams, how much will remain in the sample after $15.2$ days? I've tried solving it written out, but I keep getting the wrong answer.
Blue Note
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What will be the velocity of a photon ejected from the surface of cesium by a photon with a frequency of 6.12E14 s^-1?

For the questions, I have used the equation: $E_{kin}=\frac12\times m\times v^2$, $m_e=9.11\times10^{-31}$ kg. When I plugged in the given numbers, I got my answer but my online homework keeps marking me down. I do not understand what I did wrong.…
calimed
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Radial Acceleration Proportionality

Radial acceleration $a_c$ is given by $$\frac{v^2}{r}$$, which clearly demonstrates the inverse proportionality of acceleration and radius. It seems to me, however, that the equation: $$a_c=4\pi^2rf^2$$ demonstrates the exact opposite. Am I missing…
Tal Kodazian
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2 answers

Avg Accel problem

At a certain time a particle had a speed of 18 m/s in the positive x direction, and 2.4 s later its speed was 30 m/s in the opposite direction. What is the average acceleration of the particle during this 2.4 s interval? I tried avg accel = delta v…
user138342
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How find direction given $i,j,k$?

A proton initially has $\vec v = 8.0\vec i − 3.0\vec j + 5.0\vec k$ and then $4.0 s$ later has $\vec v = −5.0\vec i − 3.0\vec j + 4.0\vec k$ (in meters per second). For that $4$ sec, what's the direction of average acceleration? Isn't angle…
user366783
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Find unit vector

Two vectors are given by $$\vec{a} = 3.0\,\hat{i} − 2.5\,\hat{j} + 1.0 \,\hat{k}$$ and $$\vec{b} = −1.0\,\hat{i} + 1.0\,\hat{j} + 6.0\,\hat{k} $$ In unit-vector notation, find the following. (a) $\vec{a}+\vec{b} =$ (b) $ \vec{a} − \vec{b}…
user366783
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1 answer

Angular frequency - Cannot explain solution

Hello I'm learning some electrical engineering today but cannot come to the solution. $w = 2π*f$ How is: $2π*295.4 kHz = 1.86 * 106 s^{-1}$ cannot figure out what $1.86 * 106 s^{-1}$ should be
raviolican
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How can I take the derivative of $Q=C \cdot \Delta T$

How can I take the derivative of $$Q=C \cdot \Delta T$$ with respect to time $t$? note: $C$ is heat capacity and $T$ is temperature
Aziz Soldier
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Problem in a step of expansion of a expression.

I was solving a problem in which a spaceship is accumulating dust on it when it passes by a cloud. I have a doubt that how the expansion is done, using which concept? I have marked in green box.
Particle king
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1 answer

A person is dragging another person at constant velocity over a surface.

#1 If person #2 is applying a force of 200 N determine work of the kinetic friction force. Assume Person #1 has a mass of 70 kg. Assume person #1 is dragged over a distance of 5 m. #2 Determine the work done by Person #2 (applied force) on Person…
Ellie
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Hi I need help with this exercise to my mechanic physics classes

A) A traffic light with a mass of 140 kg is hung up as shown in the figure above. Calculate the forces in cables AB and AC I got answer 1.33 kN, which is the correct solution. I used trigonometry and and decomposed the forces from the…
Ice_cremy
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1 answer

Can a light-year be represented as a ratio?

Would it be valid to say that a light year is a ratio between the distance that light travels and the elapsing of one year?
Omniscient Phynial Sniper
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2 answers

Centripetal Acceleration

Here is my question: You are whirling a ball attached to a string such that you describe a circle of radius $75$ cm, at a velocity of $1.50$ m/s. What is the acceleration of the ball? Could you show an equation to solve it? My…
Morata
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Net gravity problem ... how to solve?

So far, I have: $$\dfrac{G \times(2\cdot10^{-3})^2}{\sqrt{??}} $$ ??? What's next?
user416503
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