Read about power | 290 Discussions | Page 1

  1. G

    Power of a particle on a wave

    I've marked the right answers. They mainly indicate at power carried by the particles being zero, and here is my doubt- why should it be zero? Shouldn't it have some definite value? I do understand that the kinetic energy is max at the y=0 and potential energy is max at y=A, but I don't know...
  2. N

    Power generated by an engine

    I'm really struggling with this problem. I can't understand which are the forces that i need to calculate work. Probabily when the sand falls the force of which i need to calculate work is weight force, but which is the force that carries the sand at the top of the roller?
  3. A

    B Power required to reach X velocity in X time with drag

    Hello, I wrote a program that adds force to a car like so: Engine Force = Power / Velocity Drag Force = -Velocity² Net Force = Engine Force - Drag Force = Power / Velocity - Velocity² I'd like to determine power based on how fast I want a car of a given mass to reach a given speed, for...
  4. G

    Determining the power of frictional force

    I can say that the frictional force always against the rolling sphere and the velocity is increasing for the ball. So The dot product F.v keeps on getting more and more negative, so how can the Pf remain constant? Well the velocity increases along the incline and the force of gravity is down...
  5. Shubol3D

    Calculate the output power for da Vinci's tank mechanism

    Hello everyone. I'm working on 3D animation about da Vinci tank and why it doesn't work. Please help me find out how to compute: 1: how many men need to move this machine 2: what power on wheel can produce different number of man, like 1, 2, 4, 8.. vehicle mass = 8t men strength = 60kg lever...
  6. bagasme

    B Why Isn't Horsepower an SI Unit, Despite Its Popularity?

    When we talk about engines on automotive industry (cars, motorbikes, trucks, etc.), we often refer the power produced by such engines by horsepower. But when we talk about electricity, the power is measured in kilowatts. Despite the former case is highly popular, why isn't horsepower considered...
  7. K

    Calculate the current in all parts of this electric circuit

    In the circuit below, the output is 23 W across the resistor with the resistance 6 Ohm. Calculate the amount of current in all parts of the circuit as well as the polarity and EMF ε of the unknown battery. Circuit: My attempt: I get 6 unknowns with 5 equations. I don't know how to find the...
  8. Boltzman Oscillation

    Must a load consume the entire available current or only what it needs

    So if I have a source of 5V and 20 amp then the maximum power I can get from the source will be: $$ P_{max} = 5*20 = 100W$$ but my load can only take in 5 watts, it will blow up. But, does this have to happen or does my load only take what current it needs? My guess is that the load takes in...
  9. O

    Power in Cycling Question

    OK, so I tried to relate the equation P=Fv to the given equation that Pave^2= 3(Pftp^2)/Nh. I put Nh in terms of distance to satisfy the requirement that the answer should be in terms of Pftp and distance by saying Nh = distance/Vave. I also substituted Pave with Fvage. (FVage)^2 =...
  10. M

    How to determine the power of a rotary lobe pump?

    Want to know how to get the actual power the pump needs. I can measure the flow rate by the flow meter and count the revolutions of the pump. But selecting the proper motor for the pump would be a problem. So I want to know how to determine the power of the rotary lobe pump and generate the...
  11. J

    Engineering Finding voltages in a linear circuit

    From the circuit I have: ##-v_b + v_a + V = 0## ##v_b - V = v_a## ##i_1 = (v_b - V)/R_1## ##I + i_2 = i_1## ##(v_b - V)/R_1 = I + v_b/R_2## From this last equation I get ##v_b = 10.8## and hence ##v_a = 5.8##. However, apparently that is wrong. (And hence my answers to #2 were all wrong as...
  12. J

    Introductory Circuit Analysis—power ratings

    I am going through "Circuit Analysis for Dummies". On pg 18, it says, "If you calculate the power dissipated as 0.1 watts, then a 0.25-watt resistor can handle this amount of power. A 0.125-watt resistor should be able to handle that amount as well, but when it comes to power ratings, err on the...
  13. nagyn

    Induction stovetop design: am I using these equations correctly?

    I've been told an effective induction stovetop needs to deliver about 1000W of power. I have magnet wire that can tolerate at most about 0.2A of current, and was planning on using a 60Hz wall outlet as my source (obviously I'll need to bring down the outlet current quite a bit). So the energy...
  14. Physics lover

    Maximum power in this resistor circuit

    My attempt-: So the resistance is coming to be negative.Can anyone tell me my mistake.Thanks.
  15. A

    I Calculate Retinal irradiance - from photometric units

    I have been trying to calculate what retinal irradiance value I get with a 1 blue LED system. Since the manufacturer didn´t give the spectral distribution information, I will approximate LED as a monochromatic one (using the 460 nm peak). From the datasheet, the LED intensity range goes from 6...
  16. MatheusMazur

    I Power spent to keep a spring compressed

    I was wondering, I have an engine that should keep a spring compressed. How can I calculate the power necessary for this? The work is Force x Distance, as there is no distance, there is no work, so no power... But obviously to keep the spring compressed the engine will have to produce a...
  17. M

    How is it possible to use only 1000 W to transfer 10,000 BTU/h?

    Hi, I was reading a newspaper article on the energy efficiency of commonly used air conditioners in homes. Then a doubt arose when the article informed me that there are air conditioners that have an energy efficiency of 10 BTU/watt. That means a classic 10,000 BTU/h air conditioning machine...
  18. A

    I How to calculate mechanic power a person outputs?

    Hey all, I am doing some work to brush up my acoustics and one of the problems I came across this goes like this (translated, so sorry for potential grammar mistakes although I'll do my best to avoid them): A singer exhales 0.1 Litre Air per second. The 'overpressure' (pressure difference, so...
  19. reddvoid

    What is AP layer in Ansys RedHawk? [SOLVED]

    What is AP layer in ansys redhawk ? I have list of layers I see in ansys redhawk tool, there are different metal and via layers , instances etc and there is a layer called AP in the end, What is this layer or where can I find more information bout it?
  20. M

    What is the power input of a motor pulling up an elevator?

    Homework Statement Once under way at a steady speed, the 1100-kg elevator A rises at the rate of 1 story (2.74 m) per second. Determine the power input Pin into the motor unit M if the combined mechanical and electrical efficiency of the system is e = 0.76. Here is a link to the diagram for...
  21. M

    Torque required to tilt 1200 kg mass?

    Object to be tilted = 1200mm diameter cylinder Cylinder height = 2.5 meter weight of tilting assembly = 1200 kg Cylinder is on platform which is "L" shaped and tilting point is on that corner of "L" as in attached image. Shaft diameter on which it is tilted id 63mm Angular acceleration = 0.05236...
  22. N

    China's Experimental Advanced Superconducting Tokamak (EAST)

    A team of scientists from China's Institute of Plasma Physics announced this week that plasma in its Experimental Advanced Superconducting Tokamak (EAST) would be ready to begin attempting to generate more energy than it uses, in a world first. I am dubious about more news that comes out of...
  23. N

    Deriving Voltage from the Inductor Equation

    Homework Statement L = 20mH = 20 x 10-3 H i = 40 mA for t≤0 i = A1e-10,000t + A2e-40,000t A for t≥0 The voltage at t=0 is 28 V. I have to find the equation for the voltage for t>0. Then I have to find the time when power is zero. Homework Equations v(t) = L* di/dt p(t) = L*i* di/dt The...
  24. Akash47

    Emptying a well using a pump

    Homework Statement A well has a diameter of 6 m and a height of 15 m.2/3 of volume of the well is filled with water.A pump can vacate 1/3 of volume of water from the well in 7 minutes 20 seconds.What is the power of the pump? Homework Equations W=mgh, P=W/t The Attempt at a Solution The...
  25. H

    How can I calculate the number of photons with this data?

    The problem says: A radio station emits electromagnetic wave with a frequency of 100MHz (102*106 Hz). a)What's the energy of this radiation's/glow's photon? (Solved, i found 6,63*10-26 J) b)Compare your calculation with the energy of another visible radiation/glow, with a wavelength of 600nm...
  26. D

    Determining the flow rate for a cooling system

    MODERATOR'S NOTE: HOMEWORK INCORRECTLY POSTED TO CLASSICAL FORUM, SO NO TEMPLATE I need help with the following question: Please have a look at the question and my attempt at the solution. Alternative cooling systems are considered for a large computing centre requiring 1 MW of cooling...
  27. B

    Worksheet Problem about Power (average power of a car accelerating up a hill)

    Homework Statement A 1130 kg car is initially at rest when it accelerates up a 21 m high hill. When it reaches the top of the hill it is traveling at 18 m/s. If it takes 6.5 s to reach the top of the hill, what was the average power of the car? Homework Equations W = Fd P = w/t The Attempt at...
  28. Ventrella

    I Iterating powers of complex integers along axes of symmetry

    I am exploring the behaviors of complex integers (Gaussian and Eisenstein integers). My understanding is that when a complex integer z with norm >1 is multiplied by itself repeatedly, it creates a series of perfect powers. For instance, the Gaussian integer 1+i generates the series 2i, -2+2i...
  29. Potential Energy of a Particle | Work done by Conservative Forces

    Potential Energy of a Particle | Work done by Conservative Forces

    What is a conservative force and how do you determine the work done by it. It is an interesting relation between the work done by such a force and the potential energy and kinetic energy of a particle.
  30. Ventrella

    I Mutually disjoint sets of all integer powers?

    I identified what appears to be a partitioning of all integers > 1 into mutually disjoint sets. Each set consists of an infinite series of integers that are all the powers of what I am calling a "root" r (r is an integer that has no integer roots of its own, meaning: there is no number x^n that...
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