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I have project to do about wind powered car , to be specific it's something like this :On the front i'll place a propeller and on the other end of the axle a gear . the gear will spin a dc motor that will produce 6-9- volt's next with parralel connected capacitors the voltage will charge a battery.From the battery the voltage will power on (one or two) DC motor that turns the wheels.And the car will always run against the wind, [...]The deadline for the project is in one week so i need your HELP!!!
I'm using 6V 300mA dc motor for the rear wheel's but i must find a proper generator to supply the dc motor
Sarcastic comments about the thermo and physics aside, it sounds like a fun project.
I assume the teacher will provide a strong wind source such as a large fan.
Why do all the electrical conversion? Why not just use gearing from the propeller to the drive wheel. A 100:1 ratio for starters may work.
Remember of course, the teacher is hopefully less interested in the performance of the result than they are in the process of how you approached it.
The wind speed and propeller will determine how much power you can get from the wind.
If you start with the stock motor/gear combo that came with the car, you may find yourself with a power train that can't overcome the force of the wind.
And to all the doubters, sail boats can sail into the wind, I see no reason this car can't.
[...] the propeller will be the same as at cpu cooler
p.c. can anybody tell me how to calculate if this is a real car and with 150 kg of weight and there is a wind with 5m/s velocity with what speed will move ?
Quote from: Billy on May 09, 2011, 02:23:40 PMSarcastic comments about the thermo and physics aside, it sounds like a fun project.Too bad ignoring the laws of physic don't make them go away.
the guy in the shop told me that i will gain 6V but not 300mA he said to me that there will be only 100-150 mA , so i thought that i can use the propeller with gear that will be with ratio 10:1 or 1 turn on the propeller
Reading your other posts on this board it's clear you know a good deal about electronics, but on this post you rushed to judgement and electronics do not equal physics. I had assumed the comments about unity were in jest, or from a misunderstanding that there wouldn't be a wind source provided. But perhaps it's caused by a lack of understanding.
The propeller will take power from the wind. That power can be used to move anything, including the propeller, against any level of friction or force. Since I think you're concerned about conservation of energy, think of it this way:The wind has two effects on the propeller. - One is drag that will push the car in reverse. - One causes the propeller to spin and has little net effect on the car.The distance part of the spinning propeller is key, it has a large distance per time as it goes around-and-around and this is where the power needed to move the car comes from.So we should all agree the spinning propeller provides a source of power.Given that Power > 0Power = Energy / time -- power from propeller provides limited amount of energy per secondEnergy = Force * distance -- that energy can be used to move the car a distance against the windPower = (Force * distance) / timeWe can assume Force is fixed in this case by drag on the car.Power = Force * (distance/time)Power = Force * velocity -- transferring the propeller power to the wheels allows to push against a force with a velocityVelocity = power / force -- velocity can be determined with simple algebraPower is greater than zero -- we already determined the propeller provides at lease some powerForce is fixed -- it doesn't matter how high the force isVelocity is greater than zero - the car is moving against the wind. NOTE: yes I know that moving into the wind will increase the force and a proper treatment will require differential equations, but the treatment here is enough to explain the point.
I have a degree in physics so don't need to google this, but on your prompting I did google it and found this: [Snip URL]
Well, you ought to know a bit of statistics I suppose so...In each graduating class, a few will be at or near the average.Around half would be above average.Around half will be below average.It's the latter group that troubles me, as they're the ones that makes the most errors that may influence other peoples health or even life. Which group were you in?
Sorry, but it takes a wee bit more than a week to make a working over-unity device (something like forever and a day actually).
Do you honestly believe he can succeed?