# What is Phy homework: Definition and 36 Discussions

Moscow Institute of Physics and Technology (MIPT; Russian: Московский Физико-Технический институт, also known as PhysTech), is a public research university located in Moscow, Russia. It prepares specialists in theoretical and applied physics, applied mathematics and related disciplines.
The main MIPT campus is located in Dolgoprudny, a northern suburb of Moscow. However the Aeromechanics Department is based in Zhukovsky, a suburb south-east of Moscow. In 2016 and 2018, according to the British magazine Times Higher Education, MIPT was included in list of 100 the most prestigious universities in the world.

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1. ### Critical frequency of Faraday Waves?

TL;DR Summary: A fluid on a vertically vibrating plate will, upon reaching a certain frequency and acceleration, produce standing waves on its surface. These are called Faraday waves, first described by Michael Faraday in 1831. Faraday waves are still an active area of research today, more than...
2. ### Given the potential find the eigenfunction

Hi, this was one of the oral exam questions my teacher asked so i tried to solve it. Consider y>0 the energy spectrum here is continuous and non degenerate while for y<0 the spectrum is discrete and non degenerate because E<0. for y>0 i thought of 2 cases case 1 there is no wave function for...
3. ### Hot air balloon mass including increase in mass with balloon volume

Hi guys, M can then be split up into 2 components: the mass of the payload which is known, and the mass of the wing. The wing material has a known thickness and density meaning its mass is given by: surface area of wing* mass per m^2 (mass m^2 is used as density and thickness are known so an...
4. ### Acceleration between two frames

The correct option is given as (d) I think I am able to visualize the problem but not able to put it in the equations shared above. If the the two frames are moving away from the particle at ##4 m/s^2## in opposite directions we get the acceleration between the frames as ##8 m/s^2##...
5. ### Zero velocity for a time interval, what about acceleration?

For a particle moving in a straight line, if the velocity is zero for a time interval, the acceleration is zero at any instant within the time interval. I am told the above statement is true. If I look at the equations v = dx/dt a = dv/dt It looks like if the velocity is zero for a time...
6. ### Displacement nodes for overtones

(4 / 3) * (1.8) = 2.4 = lambda 1st overtone: 2.4 / 4 = .6; (2.4 * 3) / 4 = 1.8

8. ### Find electric field separating two charged masses suspended on strings

Please help me on this question I have tried to do it many times but I end up getting the wrong answers. I have show my work what I have done.
9. ### Time period of 2 disks connected by a spring

My attempt at solving case B I've attached my attempt at case B above. What problem I'm facing is that after writing equation of angular SHM, I'm getting angular acceleration proportional to cube of angular displacement, which doesn't reduce to SHM. So how to find time period for this...

11. ### Question about gravitational potential energy and angular motion

hello I would like some help with the first part of this homework. for the moment i have done this: E initial=m*g*h Efinal= 1/2 m*v ^ 2+1/2I*ω ^ 2 Ei=m*g*h+1/2I*ω ^ 2 Ef=1/2*m*v ^ 2 my doubt is with the potential energy since it confuses me when there is or not...
12. A

### What Insights Does New PF Member Abhishekphys Offer?

Hey there , I am new member of pf. I would like to read , learn from everyone here as well as I would love to help anybody.
13. ### Find the area and length of a gold leaf

Homework Statement Gold, which has a density of 19.32 g/cm3, is the most ductile metal and can be pressed into a thin leaf or drawn out into a long fiber. (a) If a sample of gold with a mass of 3.872 g, is pressed into a leaf of 5.372 μm thickness, what is the area of the leaf? (b) If...
14. ### The thickness of glass and the longest wavelength

Homework Statement In your research lab, a very thin, flat piece of glass with refractive index 2.00 and uniform thickness covers the opening of a chamber that holds a gas sample. The refractive indexes of the gases on either side of the glass are very close to unity. To determine the thickness...
15. ### -- Calculate force at CG & away from CG

Homework Statement Hello All, Please help me to find the force required to rotate a body of 4 Kg mass from 0° to 90° in 5 second. this force is acting at center of gravity. (Image: case 1) CASE-2: Force acting away from center of gravity. (Image: case 2) Homework EquationsThe Attempt at a...
16. ### A Physics 11 Elevator Work/Power Problem

Homework Statement An elevator takes a 70 kg person from street level to the top of a 400 m sky-scraper in 4 minutes. The mass of the elevator is 500 kg. a] At what rate is the elevator plus the person gaining potential energy? b] What power is the elevator plus the person experiencing as...
17. ### What is the angle of incidence?

Homework Statement A light ray shines from a diamond (n = 2.42) into water (n = 1.33), and no refraction occurs. What is the angle of incidence? 0°30°45°60° Homework Equations sin θc = nr/ni ? The Attempt at a Solution I thought that by finding the critical angle then anything above that...
18. ### How many air molecules are there inside the tire?

Homework Statement A car tire has a volume of 10 L and is inflated to a gauge pressure of 30 psi (207,000 Pa) at 20°C. How many air molecules are there inside the tire?Homework Equations N = PV/ kbT The Attempt at a Solution (207,000 Pa )x (0.01 m3) / (1.38 x 10^-21 x 293) =5.12 x 10^23...
19. ### New wave after superposition (interference)

Homework Statement 1. Homework Statement [/B] The displacement y of standing wave that is obtained by a superposition of waves : Y1 = 3 sin (2##\pi##(0.5t - 0 25 x)) Y2 = 3 sin (2##\pi##(0.5t + 0 25 x))Homework Equations Formula for standing waves Y = 2Asinkx coswt The Attempt at a Solution Y1...
20. ### What is the Magnetic Field and Flux at Point O?

Homework Statement [/B] There is lead XY shaped as straight wire. Next to it, circular lead with radius 0.10 m. They are in the same plane. XY to center of circle, O is 0.20 m. Curent flowing through XY is 15.7 AHomework EquationsThe Attempt at a Solution 1) find magnetic field (B) at O[/B]...
21. ### A Capacitor with initial charge

Homework Statement A capacitor with initial charge q0 is discharged through a resistor. What multiple of the time constant τ gives the time the capacitor takes to lose (a) the first 1/8-th of its charge (b) 7/8-th of its charge? Homework EquationsThe Attempt at a Solution since ı know...
22. ### How to find the power consumed by the light bulb

Homework Statement (Is the image read-able now? ) The fig 1 shows the relationship between voltage and current when voltage is applied to a certain light bulb. Next, in fig 2, the bulb is connected in series with a 12-V battery and a 5 ohm resistor. Question : what is the amount of power...
23. K

### Block sliding up an inclined plane

1. The problem statement, all variables, and given/known data A block with an initial speed of 20.0m/s slides up a ramp with an incline angle of 30º. (a) (2 points) Write the position as a function of time for motion up the surface of the ramp. (b) (2 points) Write the velocity as a function...
24. ### Electric potential at the bottom of a ring?

Homework Statement [/B] A circular ring of radius "a" has a total charge Q uniformly distributed along the top half. (Q is distributed along the semicircle in quadrants I and II). What is the potential at a point located on the bottom of the ring (observation point is on the ring in quadrant...
25. ### Calculating the Spring Constant from Force-Extension Graph

Homework Statement Force Extension in (m) 1.0 0.014. 1.5 0.032. 2.0 0.053. 2.5 0.071. 3.0 0.090. 3.5 0.110. 4.0 0.130. 4.5 0.148. 5.0 0.166...
26. ### What Angle Maximizes Air Time for a 34.6m Football Punt?

Homework Statement A football punter can punt a maximum range of 40.8 m. If he instead wants to punt only 34.6 m, but maximize the time the ball is in the air, at what angle from the horizontal should he kick the ball, and how long will it stay in the air if he hits it perfectly? (neglect air...
27. ### Masses connected to spring momentum

Homework Statement An m = 1.3 kg block and an M = 3.0 kg block have a spring compressed between them and rest on a frictionless table. With a stopper in place that prevents m from moving, the spring is compressed and released so that M moves away with a speed 2.0 m/s. The spring is...
28. ### Calculating Distance Traveled by Cart with Sliding Block

Homework Statement A block of mass m =0.75 kg is set on a large cart of mass M = 6.5 kg. The cart's rollers are frictionless, but there is a coefficient of kinetic friction of 0.36 between the cart's surface and the block. The cart is at rest when the block is given an initial speed of 5.2...
29. ### How to find the FWHM-diameter of the SH beam?

Homework Statement Assume a Gaussian laser beam ( 1064 nm wavelength) having an FWHM-diameter(intensity) of 5 mm. By transmission through a thin nonlinear crystal, a new wave is generated that is proportional to the square of the incoming field (and therefore radiates at twice the frequency, or...
30. ### Solve questions on oscillations and kinetic energy

A spring of spring constant k sits on a frictionless horizontal table, one end of the spring is attached to a wall the other end to a block of mass M= 2kg, also resting on the frictionless table. Another block of mass m=450g moving at a speed of 7m/s collides in-elastically with the block of...
31. ### Centre of mass of this boomerang?

Homework Statement I have an image with the question here: http://imgur.com/TGG9VTx.jpg The red text is the answer. I haven't been able to get it without contradicting what I've been told. Homework Equations I know m1x1 + m2x / m1+m2 is centre of mass in 2d plane, but I don't know how that...
32. ### How does mass of the bungee jumper effect a safe jump

Homework Statement physics major practical, I was supposed to change the mass and find how it effects the safety of the jumper.But since hooks law doesn't follow bungee cord i really can't find a relationship.Homework EquationsThe Attempt at a Solution I used a bungee cord and hung different...
33. ### Simple Harmonic Motion equation rearrangement?

Homework Statement Hello! I have a physics homework question I just need help at! What I am supposed to do is calculate the value for free-fall acceleration, ag, for each of my trials that I did in my lab. I supposed to use the equation for the period of the simple pendulum, T=2π√l/g, but I...
34. ### Delta Dirac 3d Dimensional Analysis

1. I ´m trying to do the dimensional analysis of the Delta Dirac in 3 Dimensions. [PLAIN]http://[url=http://postimg.org/image/oif09fcd5/] 3. This is my atempt [PLAIN]http://[url=http://postimg.org/image/4qavbtv4p/]
35. ### How Do You Calculate the Surface Charge Density on a TV Screen?

Homework Statement You've probably noticed that TV screens and computer monitors have an annoying tendency to accumulate dust. Wanting to understand this better, you decide to model the situation as follows: you assume a small mote of dust might have an excess charge of 1 nC and a mass of 5...
36. ### Earth's Electric & Gravitational Field: Direction, Shape & Height

Homework Statement Earth actually has an electric field of 1.0 x 10^2 N/C at its surface pointing toward the center. (b) Compare Earth's electric field and gravitational field in terms of i) direction ii) shape iii) how it changes as height increases. c) What is the largest mass that can be...