Lost Definition and 564 Threads

Homework Statement I have a basic problem where a child jumps tangentially onto the outer edge of a stationary merry-go-round, and you have to use conservation of momentum to find the final angular speed of the merry-go-round. But the next part of the question asks "how much mechanical energy...

Homework Statement (a) Explain how heat is lost from a hot surface to the surrounding air. The Attempt at a Solution We will assume as there has been no other stipulation that the effect of radiation is negligible and thus we are taking purely about conduction. We will also assume as there...

Just want to get a poll out there about what people think this is going to be like compared to the movie. I think it will be really good.

Homework Statement Homework Equations Total Ke initial - Total Ke final = lost KE P= m1v1 + m2v2 The Attempt at a Solution Initial P : sqrt((0.08*50)^2 + (0.06+50)^2) Final P : (m1+m2)vf = 140vf Initial P = Final P and solve for vf , vf = 0.0357 KE initially : .5(0.080)(50^2) +...

Homework Statement Homework EquationsThe Attempt at a Solution The energy stored in the capacitor is ## \frac { CV^2 } { 2 }##. So, this much energy will dissipate as heat. Hence, the correct option is (a). Is this correct? It doesn't depend on the shape of the capacitor, right? I have...

Homework Statement . True or False:[/B] For a completely elastic collision of two isolated masses the energy lost is ½μνr2 Where [SIZE=16px]μ is the reduced mass of the system and νr is the magnitude of relative velocity between the two particles. Homework EquationsThe Attempt at a Solution...

Homework Statement find the initial velocity if a ball is shot at 0 degrees, goes 99.3 cm forward at a height of 25.5cm then use this velocity to determine the x distance if shot at 60 degrees at a height of 114cm part 1 Vinitial: ? delta x: 99.3cm delta y: 25.5cm degree: 0 Part 2 Vinitial...

The force of drag is proportional to velocity, but with a projectile velocity isn't constant, so how could i calculate the energy lost due to drag? The projectile in question is being shot straight upwards, so that may make this problem much more simple.

Some background: I'm currently going into my senior year in a Biochemistry/Biophysics (BB) program at a large state university. I currently have a physics minor but I'm going to end up just a few courses shy of a physics major if all goes according to plan. I'm doing very well academically -...

I have a very simple question about solar photovoltaic systems. We all know that they have limited efficiency. Suppose there is a module that is 10% efficient i.e. it can convert 10% of sunlight falling onto it into electricity. I just want to know what will happen to the rest 90%? I mean do...

Hi, I'm attempting to match prerecorded data from a guitar, to data recorded, as a user plays, as shown in the following video: The red lines are the prerecorded data, and the cyan lines are the live data. In the above example, each string is plucked open, so if you look to the lower left...

Having trouble with understanding this equation and its theory.

I have just started googling/youtubeing black holes. One point made repeatedly discussed is the loss of information in black holes. In particular quantum bits. What I have not yet found is very much explanation of what these potentially lost bits might be. So what I would like to know is...

I Have built a catapult for a 1st year engineering assignment, I know catapult are extremely energy inefficient and my theoretical catapult calculations prove that, but i don't know how to calculate the exact energy of my projectile as it hits the ground again, I can measure the projectiles real...

Homework Statement A 10kg block moving at 1 m/s hits another 10kg stationary block. Those two blocks (now stuck together) collide with another 10kg stationary block. What percent of the original energy is lost after the two collisions? Homework Equations m1v1 + m2v2 = (m1+m2)v3 Kinetic energy...

Ok, so the title was pretty vague, I'm not sure how to succinctly describe the confusion. Anyway, so I've learned that the power lost is P=I2R, and so by increasing the voltage, as P=VI and is constant, the current will be lowered, and thus the power lost will decrease. I'm confused about a...

Hi All, Please bear with me, you can skip to the LSS (Long Story Short) line if you do not want to go through the wall of text. But the complete story carries important information regarding my demise :). After a painful 7 years, I managed to obtain my PhD in Physics. My Thesis and...

Here's a new one, but in the past couple of weeks I have to reboot my windows to get the internet connection started up again. It happens with all my browsers installed, Edge (which I do not normally use), Firefox (my default) and Chrome (backup). Someplace a setting is hanging up or a driver...

When doing work on the brakes of a car or bicycle, how much of that energy is actually removed from the total kinetic energy of the vehicle? What is the most efficient braking system?

Hey everyone, Pardon the novel of a post. Short story: Got an 'A' in Discrete 1 (proof methods) using Epp's book at community college with an easier professor (the only offering for that course), and I'm understanding nothing to very little amount of information in Discrete 2 (computational...

I am in my last year (4 year total) of my physics studies, I will be graduating as the top 1 or maybe top 2 of my class. I don't have a clue what to do next. These last years I have been getting more "cynical" to say something, don't really know how to express this. I have been losing my love...

Homework Statement Homework EquationsThe Attempt at a Solution I usually have trouble with these clock problems . In this problem I can certainly rule out option d) . I considered a simple situation in which initially the clock is at 12' o clock . After 65 minutes , the minute hand would...

hi everyone! I'm new here. I was wondering how energy can be lost to friction? How would one even calculate that? Thanks!

Homework Statement "Suppose a ##1000 kg## car slides into a stationary ##500 kg## moose on a very slippery road, with the moose being thrown through the windshield. (a) What percent of the original kinetic energy is lost in the collision to other forms of energy? (b) What percent of the...

Hi I am trying to run a fast reactor model but I cannot figure out what is happening because I get the error: run terminated because 10 particles got lost. I am using the sdef card (with and without parameters) and the model is not running. Hope you can help me to fix any mistake I did. The...

I have a friend that wants to put several alternators on a car. However, he wants to gather the power from the wheels rather than the engine in order to "capture lost energy" and "save" fuel by running the AC and other electrical components off these alternators. I've already explained that...

I am completely lost. I just started my O.D.E course this week and I'm already sinking. After the first lecture I was reading through the chapter (because that normally helps) and I became even more confused. I looked at the homework, and I didn't even know where to start. Then I realized (with...

<< Mentor Note -- thread moved from the technical math forums >> I am getting stuck on this partial differential equation. Ut = Uxx - U + x ; 0<x<1 U(0,t) = 0 U(1,t) = 1 U(x,0) = 0 Here is my work so far : U = e-tw + x gives the new eq wt=wxx to get rid of boundary conditions : w=x+W Wt=Wxx...

1. Homework Statement Calculate the power lost in friction in the system shown above, with d=0.36, rpm=200, u=0.72, prop=1m and oil=0.23mHomework Equations I know p=w/t comes into it in some form, either with other equations subbed in or a derivation somewhere, but not sure. The Attempt at a...

Homework Statement After undergoing through 90° compton scattering, the fraction of energy lost by photon is a) 10% b) 20% c) 50% d) zero e) none of these Homework Equations ∆λ= h/moc (1-cosΦ) The Attempt at a Solution What i m doing is that, i get scattered photon energy and subtracting...

Apologize if you feel this question to be so simple and naive. Suppose a chamber is divided by a insulator into two equal volume (V) chambers, . One chamber contains n moles of hot oxygen at temperature T1, the other chamber contains n moles of cold oxygen at temperature T2. If you move the...

1. Homework Statement Homework EquationsThe Attempt at a Solution I did this : 1/2 (2.7x10^-6)(150x10^3) - 1/2 (1.575x 10^-6)(75x10^3) =0.143 J But the answer is 0.15 , where did I did wrong?

IMPORTANT EDIT: Mayan researchers declare story to be untrue. The Maya didn't follow astronomy to layout their cities and the 15 yr old actually discovered an old corn field. http://news.discovery.com/earth/15-year-old-didnt-discover-mayan-city-after-all-160511.htm and here's some backstory to...

I am doing a lab in my senior physics class (IB HL Physics 3-4) and I am very confused about a relationship that I found. For my experiment I dropped a racquetball from different heights and then used video analysis to find the height of the ball on its final bounce. I used this data to...

Homework Statement Q. What is the time lost in time 't' by a pendulum clock whose actual time period is T and the changed time period at some higher temperature is T' ? (T' is Time period at some higher temperature , l' is the increased length , Δθ is the difference in temperature, α is...

Hi. From an outside observer's view, any object approaching the event horizon of a black hole appears to slow down and never quite pass through the horizon. So information about those objects can always be retrieved (if you correct for the redshift). So what actually is the information paradox...

The jungle-choked remains of a "lost city", abandoned by a mysterious civilisation several centuries ago and long fabled for reports of its gold and "monkey children", have been uncovered in the depths of the rainforests ofHonduras.

Hi everyone, I apologize for the long post, and the fact that it may not be written with perfect grammar and spelling since I am not a native English speaker. I am an engineering student from France, and I am interested in pursuing a PhD in physics in the near future. It's been a week that...

[I originally posted this in Astronomy and Astrophysics but it didn't get much traction. Perhaps folks in this forum would have something to contribute...] [FONT=Georgia]I'd like to understand if and when information is ever actually lost in a black hole; specifically, I'd like to analyze the...

[FONT=Georgia]I'd like to understand if and when information is ever actually lost in a black hole; specifically, I'd like to analyze the statement: Is there information, which existed in the past, that is theoretically unavailable to external observers today due to falling through the event...

Homework Statement The rain cloud has an approximate volume of 6.50 mile3and an average height, top to bottom, of 350 ft.1 mile = 5280 ft. If a cylindrical container 6 ft in diameter collects 2 in. of water after the rain falls out of the cloud, estimate the total weight of rain that fell from...

The question in textbook:- A 4uF capacitor is charged by connecting it to 200V supply.It is then connected to an uncharged 2uF capacitor.How much electrostatic energy of the first capacitor is lost in form of heat and electromagnetic radiation? My question is that why the energy must be lost...

Hi guys, Sorry if my first post has to be one where I complain, but I am unsure about what I should do next. I started physics kind of late, after a degree in economics, at a top tier university in Europe but a public one. Our first year was horrible, VERY theoretical and we didn't do much...

Ok, I got a story for you. It's 1993 and I meet this girl at a college party. I take a liking to her and she "shares my bed." So now we're a couple. About 8 months later a friend of mine provides me with evidence that my girlfriend had advertisements in the local Santa Rosa newspaper as well...

Homework Statement sorry for the long question. Homework EquationsThe Attempt at a Solution I get everything up until it asks where the extra "half" of the power is spent. I do know that the extra half is referring to the "2" dK/dt. I have spent the last hour or so thinking about this...

Homework Statement A 1kg object traveling at 1 m/s collides head-on with a 2 kg object initially at rest. If the collision is completely inelastic, determine a) the velocity of the objects after impact and b) how much kinetic energy was lost during the collision. Homework Equations Part a)...

Hi ! I have recently graduated with a BSc in AEing. I published an article, won an international design competition, and graduated with a perfect CGPA + honors. My original plan was to work for 3 years for experience then join an MSc program to specialize in the topic. Yet it has been around 6...

Homework Statement Homework Equations Series: R_{eq} = R_1 + ... + R_n Parallel: R_{eq} = \left(\frac{1}{R_1} + ... + \frac{1}{R_n} \right)^{-1} Charging Capacitor: I = I_0 e^{-t/RC} Charging Capacitor: \Delta V_C = \varepsilon (1- e^{-t/RC}) Charge: Q = C \Delta V_C The Attempt at a...

Hi guys, I've accidently formatted my PC with lots of PST files which were on drive c:. I REALLY need to recover them ASAP. Which tools can I run in order to recover those files? I've already tried the following: 1) Recover my files 5.x - both full partition recovery and PST file 2) Hetman...

Hi. I'm getting my degree this year, and I seem to have lost all interest in learning physics. I don't feel like studying any more, I just don't see the point in it. I was fine when this semester started, I felt very motivated and I even started reading up the recommended bibliography before...