Power Definition and 998 Threads

Homework Statement A particle of mass m is moving in a circular path of constant radius r such that its centripetal acceleration a varies with time t as a = k2rt2, where k is a constant. Show that the power delivered to the particle by the forces acting on it is mk4r2t5/3. [/B] I have solved...

Homework Statement Hi, guys. I'm in a bit of a quandary. I'm trying to calculate the power a motor should have in order to move a mass a certain distance. My calculation keeps telling me that the horsepower output is much lower than my reference scenario. Here's the situation. I'm trying to...

Homework Statement Homework EquationsThe Attempt at a Solution P = 1500 * [area occupied by the cycle = ## 4 p_0 V_0 ## ] /60 = 15 kW Is this correct?

Hi I have a personal art project and I am stuck, because of very limited knowledge. I'd like to project an 1-2 meter white line from 1-3 meter distance. The projected line should be as thin as possible (3-10mm) and as powerful as possible. I created a DIY projector, but my problem is that, the...

Hi everyone, i'd like to share my packaged (plug and play) solar system project that I assembled at home. I used mostly standard parts such as a charge controller, inverter, 12 Volt UPS battery, and a pair of NEMA 5-15 R power outlets. I built the automatic transfer switch and battery...

Hello, I have a question that I've been struggling to find an answer to / understand. Probably because my understanding of physics is quite limited :) Before I ask the question, these are the things I take as facts, so please correct me if something is wrong: 1. A speaker in half space...

Most engine specifications I have found only provide the engine mass flow rate for take-off setting. For example, the V2500 has a mass flow rate of 354.25 kg/s. How does the flow rate vary through different power settings? For example, if the engine is on idle, will the mass flow rate be 0...

There are three geothermal systems that are commonly used: sry steam, flash steam, and binary cycle https://www.eia.gov/energyexplained/index.cfm?page=geothermal_power_plants . What are the efficiencies of the plants from best to least effecient on average?

Homework Statement [/B]Homework Equations For the 1st part Ohms law and resistance across zener is 10V[/B] I can't get 2nd The Attempt at a Solution For 1st part I took Vi/p = 18V[/B] Putting KVL for left loop of source-->collector-->base-->zener-->ground 18 = Vcb + 10 So Vcb = 8V And Vbe =...

Homework Statement I read in my notes that "The physical size of a synchronous generator of a particular rating is larger than one of a lower rating" Why is this so ? The Attempt at a Solution Is it because a larger one would be able to supply more power and therefore the rating would be higher ?

Homework Statement An E field with f = 2.45*10^9 Hz passes through a material with the following properties e_r = 10 u_r = 1 sigma = 1 (S/m) The Incident E field has peak magnitude of 300 V/m at the air to surface boundary. (a) *solved* Find the incident power density at the material...

Solar generation results for US are out for 2016. Year over year: http://www.eia.gov/electricity/annual/html/epa_01_02.html US: Net Generation (Thousand Megawatthours) 2014 Solar: 17691 (that's 0.43%) All sources: 4093606 https://www.eia.gov/electricity/annual/pdf/epa.pdf: US: Net Generation...

Homework Statement For a positively-charged particle at the origin, and a negatively-charged particle lying to its right on the positive x-axis, the electrostatic force on the negative charge is attractive, and Coulomb's Law gives the magnitude of that force: F = k |Q1| |Q2| / x^2 k is...

Homework Statement The lawn tractor in figure 18 goes up a hill at a constant velocity. Calculate the power that is developed by the tractor. Mass: 120.0 kg Angle of incline: 21 degrees Distance: 12.0 m Velocity: no velocity given other than it is constant Time: idk Homework Equations None...

1. The problem statement, all variables and given/known da Show that for a PV cell finding a maximum of power leads to the following equation: ##(1 +\frac{qV_{max}}{kT})\exp\left(\frac{qV_{max}}{kT}\right) = 1 + \frac{I_{sc}}{I_{rs}}## ##I_{sc}## is short circuit current and ##I_{rs}## is...

Homework Statement I'm using a force of 392 pound feet of force to move an object that weighs 250 lb a distance of 22 in in 1.3 seconds.. how do I determine how much power was consumed in this move?[/B] Homework Equations Power = force * distance/ time The Attempt at a Solution 749 watts

Electrical generation plants produce large amoounts of power to serve millions of people and many thousands of factories. I know very little about how such power is regulated and I always wonder how such large power output can be instantly regulated to accommodate the many instant changes in...

I would simply like to know: Given a lossless transmission line with a certain characteristic impedance Z terminated in a load L. How can I go about computing the fraction of the time average incident power arriving that is dissipated in the load? Is this possible without knowing the voltage or...

Homework Statement Force of 200 foot pounds of torque is being exerted on a axle of a disc which is turning at 1.57 radians. The disk has a moment of inertia of 234 kg per meter squared and it's 1.5 inch diameter axle has a prony brake installed applying a load of 200 foot pounds of torque at...

Homework Statement A coaxial transmission line consists of an inner cylindrical conductor of radius a = 1 mm and a cylindrical outer conductor chosen to make the characteristic impedance 75 ohm. The space between the conductors is lled with a gas which can stand a maximum eld of 105 V/m without...

Hello, I was thinking that using AC to supply power to a lamp would cause it to flicker, considering that the potential difference keeps changing signs. This would mean that the current supplies voltage to the lamp, only to take it back after a really small amount of time. Voltage say's...

Homework Statement v = 141.4sin(wt + 15) i = 14.14 cos(wt - 45) Homework Equations Draw Phasors. P = VI cos(theta) Q = VI sin(theta) S = P + jQ theta is angle between V and I The Attempt at a Solution [/B] V = 141.4sin(wt + 15) So Vrms = 141.4/1.414 sin(wt + 15) = 100 sin (wt + 15) I = 14.14...

Say you (a skilled motorcycle racer) ride a motorcycle in a big empty parking lot and ride in a big circle of constant radius and slowly go faster and faster. If you are careful as you go faster will you all of a sudden go from very little power slide to a lot of power slide like the video...

Hello all, I need to know what is the difference between the percent power and efficiency for air compressor. Is it the same or what is the relationship between them. Thanks

The power series $$\sum_{n = 2}^\infty \frac{(n-1)(-1)^n}{n!}$$ converges to what number? So far, I've tried using the Ratio Test and the limit as n approaches infinity equals $0$. Also since $L<1$, the power series converges by the Ratio Test.

Homework Statement A force applied to a tennis ball is described by the function F(x) = 2x + 5, with the force in Newtons and the position in meters. How much work does the force do on a tennis ball as it moves from -2.5 m to a new position of 2.4 m? Homework Equations F(x)= 2x+5 force x...

Alright, I'm trying to calculate the power requirements for a 30 Weber =( 30 Tesla/m2) Strong magnet According to this document it would require about 88 MW using a steady-state copper coil magnet The question is, how much power is required to do the same using cryogenicly cooled...

Homework Statement A force of 2i + 5j moves from (2,5) to (4,7) in 3 seconds. Find the power of the force. Homework Equations Power = Fv The Attempt at a Solution |F| = sqrt 29 v = (sqrt 8)/3 Power = 5.077 w

Good morning at all, I have to do one research of the transport of large nuclear reactors, and I need to have an idea of which is the DIAMETER, HEIGHT and WEIGHT of the reactor I think that there are a lot of different dimension, but i want to know only approximately, because i don't have...

Homework Statement Choose one form of electrical generation and in point form outline the process through which electricity is generated and the energy transformations that occur. Homework Equations NA The Attempt at a Solution Hi, I am done my work and I used two reliable sources. This...

building a DC supply with a load voltage of 3.3V and load current of 3.3mA. all the books and schematics I'm seeing is that they're putting the fuse in the primary of the transformer, why? if i were to fuse the primary as well how do i get the rating of the fuse that i'll need? its said in my...

Homework Statement With just about any problem asking for "rate at which source is delivering electrical energy to the circuit" or "find the power of the circuit" in a LRC circuit, I get that you have to calculate for the average power. But the multiple equations confuse me - sometimes in...

Homework Statement A series circuit has an impedance of and a power factor of 0.720 at 50.0 Hz. The source voltage lags the current. What circuit element, an inductor or a capacitor, should be placed in series with the circuit to raise its power factor? Homework Equations cosΦ=R/Z...

[FONT=verdana]A sphere of mass 1.9 kg and radius 0.5 m is attached to the end of a massless rod of length 3.0 m. The rod rotates about an axis that is at the opposite end of the sphere (see below). The system rotates horizontally about the axis at a constant 422 rev/min. After rotating at this...

Consider the summation ∑,i=0,n (t^(n-i))*e^(-st) evaluated from zero to infinity. You could break down the sum into: (t^(n))*e + (t^(n-1))*e + (t^(n-1))*e + ... + (t^(n-n))*e ; where e = e^(-st) To evaluate this, notice that all terms will go to zero when evaluated at infinity However, when...

I have recently had to adopt hearing aids. I shall soon be taking them back to supplier for adjustment/repair/replacement of one of them. What seems to happen is that with new (lithium) battery it gives sign of life and some amplification into the right ear, but after a few hours there is no...

Is fusion power still considered to be the most powerful energy source possibly achievable of technology by mankind, or there is any other type of fuel that has passed it? I'm not looking for anything outrageous like a hurricane engine or a black hole engine, but some kind of reaction scientists...

Homework Statement I am working on the following problem: And ideal single phase transformer 240V/2880V is supplied with a 240V source via a resistance cable of 3ohm. If we connect a R=720ohm resistance to this, determine the primary current and the dissipated power in R. (I'm sorry if some...

Homework Equations P = W*V Fnet = ma V = 3.0 m/s W = 29.9[/B]The Attempt at a Solution I think i got this wrong, but I want you to check if my answer is right :( Heres what i did: So, P = force * velocity P =force*3.0 m/s force = force due to gravity + acceleration (net force) is F = ma =...

Homework Statement At what rate is the gravitational force doing work on a 2.0 kg projectile at an instant when the velocity of the projectile is 4.0 m/s directed 30 degrees above the horizontal. the answer is -39 W but i need help on why! Homework Equations P = W/T Power = Work*V...

Homework Statement A circular loop of radius a and resistance R is placed in a changing magnetic field so that the field is perpendicular to the plane of the loop. The magnetic field varies with time as B(t) = B_0 * e^(-t) where B_0 is a constant. Determine the electrical power in the circuit...

How to calculate following input and output parameters- 1. Input at starter motor - Drive torque and power as shown below 2. Output at flywheel axle - torque, power, Kinetic energy, centrifugal force as shown below Input parameters: starter motor rpm -3600, Gear ratio- 18: 1 if any parameter...

Homework Statement Homework EquationsThe Attempt at a Solution Using Stefan Boltzmann Law , The power emitted per unit area by the small sphere is P/A = eσT4 . The power absorbed per unit area by the surface is given as P/A = eσT04 . How should I use the distance between the two surfaces ?

Hi everyone - here's a concept that I'd like a few opinions on: As part of a project, I'm looking at using a brushless DC motor mounted on a high-speed vehicle as a generator. Once the vehicle hits its top speed, the batteries should disconnect from the motor and the vehicle's own velocity will...

Midland Nuclear Power Plant was going to have two nuclear reactors from Babcock & Wilcox. Unit 1 was to have a capacity of 460 MWe, while Unit 2 was to have a capacity of 808 MWe. Were the reactors twins that simply had different steam machinery due to the cogeneration requirements or were they...

Homework Statement 1. A sinusoidal source with RMS voltage V = 11Volts across a resistor R = 50Ohms, determine the dBm value. Hint: you will first have to determine the power delivered and then check the formula for dBm calculations. 2. A type of coaxial cable has a loss of 12dB/100m at some...

Homework Statement Is there a power factor convention when it comes to the angles of a given current and voltage? In one class I learned that PF = cos(θ_V - θ_I) but in another the professor claims (I still think he is wrong) the convention for that class is PF=cos(θ_I - θ_V). Here is a...

Let's assume you have a perfectly insulated closed liquid loop with a pump who's motor is cooled by the liquid its pumping. Assume steady state operation, so the pump is operating at some pressure difference and flow rate based on intersection of pump curve and back pressure curve. Does this...

Thank you in advance - as they say - to ANYONE who can help me figure out how/whether a small solar solution could help my brother in Puerto Rico. Still no water/power. Just candles and a garden hose with "water". I have info overload from DIY sites. Can an average person set something up for...

Homework Statement Two 110-V light bulbs, one "25W" and the other "100W" are connected in series to a 110 V source. Then: a. the current in the 100W bulb is greater than in the 25W bulb b. the 25W bulb will be brighter c. the current in the 100W bulb is greater than that in the 25W bulb d. the...