How many bowls of Fruity Pebbles would it take to power the rockets in a space shuttle for 1 second??? There is 9,600 horsepower in one rocket on the space shuttle and there are two rockets on the space shuttle. There are 150 calories in a bowl of Fruity Pebbles.
22813, assuming efficiency. http://www.wolframalpha.com/input/?i=(9600+horsepower+times+2)/(150+calories)*1+second
correct 9600 Horsepower x 2 Rockets x 8 calories / 0.0449 / 150 calories x 1 bowl = 22806 bowls of Fruity Pebbles
I really like the basic idea of the question, but many things went wrong in this thread. While the replies correctly combined the power, energy content and time provided in the opening post to give a result in a number of bowls of Fruity Pebbles, this result is meaningless. It has no relation to reality or the performance of the space shuttle engines. Let's do some rocket science! First of all, power is not a good choice to measure rocket (or jet) performance. Rockets essentially produce thrust, a force, that accelerates the rocket. This force is the reaction to the force required to push stuff out the nozzle at the rear end. The more stuff (usually hot gas, but it could be anything) you push out, the higher the force. The thrust can also be improved by increasing the speed at which that exhaust leaves the rocket. Increased exhaust velocity also results in a higher efficiency of the rocket, that is, you need less fuel to get the same amount of thrust. The space shuttle actually starts off with 5 rocket engines. There are 3 engines at the back of the shuttle, burning liquid hydrogen and liquid oxigen, and two rocket boosters, burning solid fuel (APCP). The solid rocket boosters (SRB) of the space shuttle have an exhaust velocity of about 2550 m/s (specific impulse, Isp = 260s), while sugar rockets only get half of that due to the different chemistry involved, 1180 m/s (Isp = 120s). In other words, sugar rockets need to burn about twice the amount of fuel to get the same thrust when compared to the space shuttle SRBs. One space shuttle booster provides about 12 MN (meganewtons or millions of newtons) of thrust. The amount of fuel and oxidizer burnt per second (let's call it dm/dt) can be calculated now. dm/dt = 12 MN / 2550m/s = 12*10^6 kg*m/s^2 / 2550m/s = 4700 kg/s A sugar rocket requires to burn more fuel and oxidizer to achieve the same. dm/dt = 12 MN / 1180m/s = 10200 kg/s Since rocket candy usually has a 13:7 oxidizer to fuel ratio, this means that 3400kg/s of sugar burn in each booster or 6800kg/s in both. Assuming 37g for one bowl of fruity pebbles with 150 calories, you have to burn about 183000 bowls of fruity pebbles per second to achieve the thrust of the space shuttle SRBs (without the three main engines). In total, you would have to fill the SRBs with 22 million bowls of fruity pebbles to maintain that amount of thrust for the whole burn time of the space shuttle SRBs. Warning: Rocket candy, the mixture of sugar (fruity pebbles) and oxidizer (potassium nitrate) may sound delicious, but it's both flammable and toxic! Unfortunately, you can't just build sugar boosters with twice the amount of fuel compared to the space shuttle boosters and get the same result. Why? Most of the thrust is used to accelerate the fuel that is still inside the rocket. The more fuel you have, the more fuel you need to accelerate the fuel you still have. In practice, rockets are usually more than 90% fuel by weight at lift-off. Under those circumstances, twice the fuel doesn't make your rocket twice as fast in the end. This is the reason why rockets designed to go into earth orbit or beyond are rather large contraptions. You could say that rockets are mostly fuel accelerators. Mathematically, this is expressed in the form of the rocket equation. References: https://en.wikipedia.org/wiki/Space_Shuttle_Solid_Rocket_Booster https://en.wikipedia.org/wiki/Rocket_candy https://en.wikipedia.org/wiki/Specific_impulse https://en.wikipedia.org/wiki/Tsiolkovsky_rocket_equation https://www.postconsumerbrands.com/wp-content/uploads/2016/09/Pebbles_FruityPebbles-1.pdf Finally, the main ingredient in fruity pebbles is rice, which contains carbohydrates other than sugar (sucrose). I don't know how well rice performs as rocket fuel. Since I haven't found any data on that after a quick google search, I guess that it's worse than sugar, which means that the above calculation is probably an absolute best case scenario. You might need much more than that.
