Flunch

doG is right - almost any AC generator in common use will run at a fixed speed in order to generate a constant frequency output. I believe you're on 50Hz in Europe so a common engine speed there is 1500 rpm (4-pole generator) I don't know what size generator you have but 15mm pipe seems pretty small. You want to ensure you don't create excessive backpressure on the engine. You can measure the pressure easily by installing a simple water manometer near your engine exhaust outlet.

complete and utter crap

I have a proof of this in a physics text. You should definitely believe it.

with a sextant you can get your latitude from the position of the stars, measuring angles to the horizon. you need to know the time at your present position and at the prime meridian in order to determine longitude as well. this is why ships carried chronometers in the old days.

When the world starts to seriously strain its remaining oil reserves nuclear will be the only viable alternative for large scale energy production. wait and see. arkain101, pick ONE of those ideas, and develop a device for increasing the efficiency of ONE of those processes that costs LESS to manufacture (in financial and energy terms) than it does to pay the incremental energy cost and you'll be a rich man.

whichever one turns faster. in an old fashion dogfight that's what matters. otherwise, whichever one has longer range air-to-air missles and better radar or stealth technology

When something falls while it is moving horizontally you can consider its motion in both the vertical and horizontal directions SEPARATELY. i.e. it's like dropping the car 46 meters from rest PLUS making the car move forward 138 metres in a separate event. So this car is going to fall vertically 46 metres. Use your motion formula to calculate how long it will take to fall straight down 46 metres from rest to the ground below. d = 1/2*a*t^2 remember a is the acceleration due to gravity here. now you'll have the time it took for this car to fall. This is also the time it takes the car to travel 138 metres to rest from the edge of the cliff out, in a horizontal direction. Knowing this you determine the speed of the car when it left the cliff using the basic equation v = d/t. Make sense?

your teacher probably wants you to calculate the distance travelled (circumference of the orbit) and divide it by time of orbit to get velocity ... then use the centripetal acceleration formula given by Klaynos... this acceleration acts toward the centre of orbit.

dragono, you'll need the first law of thermodynamics. U = Q-W The change in internal energy in a system is the heat ADDED to the system minus the work done BY the system. You'll also need to know the specific heat capacity of water and the formula: Q = m * c * T It will also help you to know that a Newton-meter is a force applied over a distance... which is WORK... (aka Energy). A newton meter is a Joule. See what you can do with that much info

OnlyThorns, In Klaynos's equation: s is distance u is velocity a is acceleration t is time these are typical variables used for these factors in Newtonian physics - even in north america but you can rewrite it as d = vt + 0.5a*t^2 so solving for the horizontal motion (as Klaynos said we neglect air resistance so we assume the acceleration is 0... this makes the second half the equation go away). 19 m = 25 m/s (t) t = 0.76 seconds Now look at the vertical motion: Put 0.76 seconds into the original equation. Initial velocity in the VERTICAL direction is zero so now the first half of the equation goes away. Put in 9.81 m/s^2 for acceleration due to gravity and solve for d. This will be the height the ball falls during the 0.76 seconds it took to move forward the 19 metres... and thus the height at which the racket contacted the ball.

Starting point for any classical mechanics problem: Draw a "free body diagram". Use component vectors to show tension in the rope and its horizontal and vertical component forces, along with the angle made by the rope with respect to the horizontal plane.

The problem, as I see it is that escape velocity is what, 11,200 m/s? So even at a constant 3g acceleration your rail gun would be 2131 km long. That'd be expensive... and I don't even want to spitball how much power it would require.

If I recall correctly, the recrystallization temperature of steel is 727 C. That is how hot it needs to be in order for the molecules to have enough energy to re-align the micro-structure, creating different forms of steel. that's HOT

Externet is right, you need to master the concepts of voltage, amperage and resistance first. Think of voltage (pressure) as what causes electrons (or water) to flow. The flow is the current. As current or water flows through conductors (or pipe) the voltage (pressure) drops because of resistance (electrical or frictional). So across any resistor we can measure a voltage drop. Voltage will continually DROP as current passes through increasing resistance of a circuit. The total of the drops across all resistors (including the small resistance of the conductors) will be the voltage of your battery. For elementary purposes you may decide to ignore the resistance of the conducting wires because they are very small reletive to say a 3 ohm resistor in your simple circuit. Also remember that Power (P) = Voltage (V) x Current (I). A 1 amp current flowing between a potential difference of 9 volts constitutes 9 watts of power. If the same current flowed between a potential difference of 5 volts, you'd have 5 watts.