Watts Definition and 143 Threads

The above is just an example question to describe the situation. I am doing some simple calculations, but I think I am missing something. Is anyone here familiar with decibels? It is a coax cable and I'm working at ~20 kHz where attenutation isn't listed on the data sheet -...

As a high school student, I remember getting tickets to the Tattoo You tour. I was going redeem a voucher to buy tickets in New York City (these vouchers were distributed by randomly selected self-addressed stamped envelopes). A few blocks from the box office, I was offered $500 for my voucher...

A capacitor based fan regulator is rated for maximum 100 watts. What components need to be replaced to make it suitable for 500 watts or 1000 watts...

My understanding is that electrical devices are rated in watts which is really watts per second. For instance if a peltier module is rated at 5 watts it will use 5 watts per second. I had thought that it should be simple to convert kilojoules to watts but everywhere I’ve looked i can only find...

Human power 97 watts? 2000 kilocalories is the average human need per day. 2000 kilocalories is 8373.6 kilojoules divided by 86,400 seconds in days = 97 watts.

Setting aside whether this works or not, can someone here compute the output in watts-?

Hello all, I am in deep water here based on my very fundamental understanding of physics generally and solar design specifically. I am 83 years, homeless, and have access to land with one building, wood heat, non-potable site water, and nothing else. I want to make a PV system with an array...

I took Electricity in HS and Electronics in Continuing Ed, and I still get tripped up over this very basic question. A household circuit with no resistance - a short - will allow enough current through to burn it out. A household circuit with a giant resistor can power a tiny nightlight, by...

From what I've read, it says that high current is dangerous. So my question is if you had 1v and 10amp, would it be more dangerous than 10v and 1 amp? Shouldn't they be the same? Why don't we say high watts are dangerous?

Homework Statement Imagine a maglev train car on a track. The train car weighs 1000 kilograms and travels at 10 meters per second. Without any external force, the train car slows down to 5 meters per second in 10 seconds. How much force does it take to return the train car to traveling at 10...

If the moon were a light bulb how many watts would it be.

Homework Statement A 4.0 Watt toy motor is connected to a secondary circuit of a transformer with 60 loops and a current of 0.10 A. The primary voltage is 120 V Homework Equations Vp / Vs = Ip / Is Ip = Pp / Vp[/B]The Attempt at a Solution 1. [/B]Vp / Vs = Ip / Is 120 V / 40...

I have lots of batteries 12 volt charged by the sun what I need is something that would draw 100 watts and give heat when connected to a car battery? I have ac heating pads, 2000 watt hot water elements lots of copper wire, light bulbs any other ideas?

I have a question about work. If Newtons 3rd law of motion states there is an equal and opposite reaction for any force. Now if for example I apply 500 Newtons of force on my dresser and move it 5 meters I used 2500 joules of energy. Now because the dresser is equally putting that much force...

My colleague has been developing a hybrid water/forced air heat transfer system for a prototype lighting solution we are developing. I am struggling to get my head around the calculations required to figure out exactly how many watts of energy (heat in this case) are being transferred to the...

Is there a way to determine how many amps / watts is required from an electric motor in order to move (lift, push or pull) an object weighing a specific amount? Conversely, is there a way to determine the maximum amount of weight an electric motor can move (lift, push or pull) based on its...

Homework Statement A stereo amplifier is rated at 130W output at 1150Hz. The power output drops by 10.0dB at 15.3kHz. What is the power output in watts at 15.3kHz? Homework Equations R=I/Io Io = 10^-12 w/m2 bel = log(r) The Attempt at a Solution I have no idea where to start

I am just curious on this one, if you could efficiently turn matter into energy (the whole e=mc2 thing) how much energy could you get per gram?

So, I know the basic equation of W=V*A, but how would I physically do this in a circuit? Say I have 90W=19V*4.74A (http://www.chargerbuy.com/replacement-hp-90w-smart-ac-adapter-19v-474a.html?gclid=CjwKEAiAi-_FBRCZyPm_14CjoyASJAClUigOPligEwQ9DD87xaDL8SQcvxNtWCeo_2nl68GmdozOoxoCbW3w_wcB) for...

Hello, I have problem. I'm haveing my soldering iron tips oxidize very fast. I need to know what wattage to use to get melting point of solder. I think I'm overheating my tips. The melting point of the solder I have is 221C (430F). Is there a formula to calculate temperature from wattage input...

Homework Statement Fast-flow blood warmers (pictured below) can be used to heat blood products (carefully and uniformly) when rapid, high-volume transfusions are necessary, in order to prevent hypothermia in the patient. The blood product density and specific heat can be assumed to be 1.12...

Homework Statement Homework Equations RL = 20 log10(Vrms) - OCV For this hydrophone OCV = -211dB The Attempt at a Solution 1. RL = 20 log10(Vrms) - OCV RL = 20 log10(3.5mV) - (-211) RL = 161dB re uPa 2. 20 log10 (uPa) = dB Pa = 10^(dB/20) X 10^(-6) = 10^(161/20) X 10^(-6) = 112 kPa 3. ...

Hi Air conditioner vs evaporative cooler: ratio of (BTUs/hr) / electrical watts I know evaporative coolers do not state BTUs/hr. I do not know why. Did anyone try them and record time taken to cool. I found this example, but I do not know if it is practically relevant...

Hello everyone :alien: I have been assigned to create a physics problem involving bicycles. I thought up the following, but I had questions regarding if it was properly made / worked out. A cyclist is accelerating constantly up a slope at 1 m/s ^-2 The slope is at a 15 degree angle and is 30 m...

Homework Statement A typical electric blanket consumes 50 W of power when operating. What is the overall resistance of the blanket if it is designed to be plugged into a standard powerpoint? Power = 50 watts Voltage = 240 v (standard powerpoint) Homework Equations I (current) = Voltage/...

Thanks to anyone kind enough to help check my logic. Using 13 gauge copper wire and a magnet I can generate .05 watt every time the magnet passes the coil (according to the voltmeter). Am I correct in assuming that if the magnet passes the coil 60 times a minute, then (.05 watts X 60rpm X 60...

With Watts Bar Unit 2 expected to begin operating this month, will it have any significant effect on the industry? It's somewhat a milestone.

Could anyone help me with this sum - To generate electricity, 180000 kg water is dropped from a height of 50 m (let g = 10 m/s^2). If half the gravitational potential energy is converted to electric energy, how many 100 W bulbs can be lit ? Formula - Ep = mgh I calculated the potential energy...

Hello all, I've currently got a swirly CFL bulb that I lit up wirelessly and took some measurements of using a light sensor which returned the data to me in lux. How can I get from lux to watts? As I understand it, lux is a measurement of lumens per unit area, so do I have to somehow find the...

Hello, Sorry for a newbie Q. If I have a 340ah Lithium LifeP04 12V battery in my camping trailer... its BMS set to 5% (for a drainage of 95% = 323 usable amp hours)... it is hooked to an inverter claiming to have 88% efficiency... how many AC watts (@ 120V) can I expect in theory, or...

Homework Statement Assume that a 14 kg sample of 240Pu is used to produce electrical power from its α decay. If your device is 60% efficient in producing electrical power, how much power can be produced? (in watts) Homework Equations Q=mass of plutonium-mass alpha-mass daughter; 240 plutonium=...

Homework Statement A system consists of a bicycle and a cyclist traveling at a constant velocity along a horizontal road. The total resistive force acting on the system in 4.0N and its speed is 8.0 m/s. Calculate the useful power output of the cyclist. The cyclist stops pedalling and the...

If a motor is such-and-such Hp or kW, is that the Output power, or the Input power?

Homework Statement I have a question that involves comparing the energy output of a laser to the energy required to make tea. I've already calculated the energy to make tea and I know what to do to find how long it takes to make the tea but I'm struggling with the energy output part. It says...

Good afternoon everyone! I've exhausted my initial ideas for supporting 1500 watts of power in the trunk of my car, for intermittent use with a wall plug connection. My first thought was a simple power inverter, however, ideally I won't be running this power from my car battery. This has proven...

Hello. I am not an engineer but would really appreciate some help with a calculation for my PhD in biomedical sciences. I have a new exercise ergometer (see picture) and have been able to obtain the force applied (Newtons) to the load cells located underneath each foot pedal at 1hz. A motor...

A 60W lamp and a 120W lamp each have a potential difference of 120V across their terminals. a) What is the current through each lamp? I think you use the formula I = P/V and so: Lamp #1 = I = 60/120 and Lamp #2 = I = 120/120 But I don't know if that is right? Thank you so much for the help!

< Mentor Note -- thread moved to HH from the technical physics forums, so no HH Template is shown > I have read every post I've found on here about this subject, but for some reason the answer is elusive - I suspect due to an issue with units. Here's the problem. vInitial = 0 meters / sec Mass...

Hello. New here and trying to figure out if my formula is right. I'm a controls guy so this other stuff keeps me on the ropes! Trying to heat 179lb's of steel 1440F in 30 minutes and find wattage needed. It appears the formula is: #Lb's X specific heat X differential temp 3.415 x .5 (minutes)...

so basically i have calulated some forces in Newtons at one second intervals i have time - 1, 2, 3, 4, 5, ----- 5 seconds total distance - 3, 12, 27, 48, 72 ------ 162 meters total force = 1804, 1822, 1849, 1866, and 101 Newtons energy= 5411, 16'369, 27'736...

How can a microwave I took apart have a .9 microfarad capacitor rated for 2100v? The microwave is rated at 1800 watts. What am I missing? 1/2 CV*2=1.98 joules

A guy told me that a watt is not associated with heat. Then I read that a watt can be defined as 1 J/s of heat flow. Wouldn't that mean a watt is IS associated with heat? I think the guy was trying to say that a watt is associated with multiple forms of energy, not heat, specifically. I'm...

I believe I understand that you cannot directly connect watts to lumens because although they could/may be related, they represent different quantities (I guess it's akin to comparing height and weight measurements for a person). However, given the same exact light bulb, typically the higher the...

I've been trying to brush up on my electrical engineering skills and have been working on the circular and redundant terminology of amps, volt, ohms and watts. It seems to me it all comes down to a quantity of electrons (i.e. coulombs). And, for various reasons perhaps the number of electrons...

Hey all, I'm having some unique challenges on an optical system I've created, where I'm arraying several LEDs under 1 optic/reflector. We're beginning to see major degradation of the metallic coating that is applied to the part, and I'm tyring to quanitfy the temperature (converted from radiant...

If given the decibels from the thunder and the distance away the lightning struck, would it be possible to tell the amount of electricity in that bolt of lightning? If so, a formula would be much appreciated.

Hi, I am a bit confused about what exactly is being produced when someone uses a hand generator. I know P=R(I^2). Does this mean that if I have a hand crank that can produce 1 amp I can use a 200 ohm resistor and produce 200 watts of power. If this is the case it seems as though producing any...

Radial Flow Water Pump--How to calculate Watts required to power it Hi all, I'm currently working on an independent project where I'm building a radial flow water pump to be sent to a village in Senegal. I'm having trouble figuring out what motor to use to power this water pump and how much...

Homework Statement The power available (output) is measured by the velocity at which you are moving and the thrust required to create that movement. NOTE: Conversions for proper units are provided below equation. Power Available: Pout = Tc * v where: Pout = power available (watts) Tc...

I am working on a small project and having those values shown in real time on the device will be helpful. I don't have much room as it is. I currently have one of those little 1s-6s volt meters used by RC hobbyist and use my multimeter to check resistance. My goal is to have something around...