Power Energy

Efficiency of an LED given a data sheet?
Data sheet: www.avagotech.com/docs/AV02-1640EN I have to measure the efficiency of a solar panel under different colours of light, in terms of the number of photons entering the solar panel to the number of electrons converted to energy. To calculate the number of photons leaving the LED, I'm going to use the following equation: Photons per second = Power/Energy Power is in joules per second Energy is in Joules Energy = hc/lambda h is plancks constant c is the speed of light lambda is the wavelength of the light Power = VI Where V is the voltage through the light I is the current in the circuit The circuit is in series with a resistor, therefore: V=IR V=I(R(r) + R(L)) V/I - R(r) = R(L) V(t)/I - R(r) = V(L)/I V(L) = V(t) - R(r)*I Where: V(t) is total voltage V(L) is voltage through the light R(L) is the resistance of the light R(r) is the resistance of the resistor There is also a graph I have modelled as a polynomial which gives the relative luminous flux at different wavelengths, as all my data on the sheet is correct to the other values. As I will fix the current in, I will take this as an equation constant. I have also ensured that I am taking the area under the graph as a fraction of the whole area based on the distance from the solar panel to the LED, and am also taking into account the area of the LED. SKIP DOWN TO HERE FOR MY ACTUAL QUESTION: I am assuming in my analysis that the LED is 100% efficient, and produces no heat. I also have disgregarded luminous efficacy, and am wondering if the relative luminous flux will be dimmed in the cases of the blue light for instance. Can anyone help me to factor in these two parts? Thanks

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Physics Help Anyone? Totally lost...?
I am TOTALLY lost on this physics homework. It involves power, energy and forces. Any geniuses here to help out? 1) A 60kg box is lifted by a rope a distance of 10 meters straight up at a constant speed. How much power is required to complete this task in 5 seconds? 2) a 1994 ford mustang is driving down a road with a constant speed of 30 m/s. The engine must exert a 5000N force to maintain its speed. (m=1460kg) What is the power rating of the engine? 3) How long would it take a 7.5 Killowatt motor to raise a 500 kg piano to an apartment window 10 meters above the ground? 4) The trains on a rail car are raised 10m above ground at the loading platform to a height of 60m at the top of the first hill in 45 seconds. Assume that the train (including passengers) has a mass of 2,500kg. Ignoring frictional losses, what power motor would be required to accomplish this task? Additional Questions: 5) an 82kg hiker climbs mt. humphrey near flagstaff. during a 2 hour period, the hiker's vertical elevation increases by 540m. Find the power generated to increase the hiker's Eg. 6) Jim and Bob are two workers being considered for a job at the UPS loading dock. Jim boasts that he can lift a 100kg box 2 meters vertically in 3 seconds. Bob counter with his claim of lifting a 200 kg box 5 meters vertically in 20 seconds. Which worker has the greater power rating? THANK YOU SO MUCH! Easy 10 points?

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Measuring Electricity?
I have my Electricity (grade 9) test tomorrow. I know Power= energy/ time (P=E/T). But how do you find out the time if you are only given E and P, or find E with only P and T???

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