Question

Using an unmanned rocket to visit the space station requires 85.2 trillion BTU of energy. The best fuel for the mission will have the highest ratio of energy to volume. Based on the fuel data presented in the table, select the optimal fuel and calculate the total gallons of fuel required.
Table: Energy Output BTU/lb Density g/ml
Kerosene 18,500 0.820
Gasoline 20,900 0.737
Ethanol 11,500 0.789
Hydrogen(l) 61,100 0.0710
Which is the optimal fuel?

How many gallons of fuel are required?
Conversion units:convert energy output to BTU/gal
i need help please

Answer 1

This is a big hairy unit conversion problem. You are given BTU/lb and density in g/ml and asked for something in BTU/gal. So no need to panic. Set up the unit conversions systematically, You know where you want to end up (BTU/Gal) all you need are the conversions. You can look them up with Google.
Take the first one, 1800 BTU/1lb x (?lb/?g) x 0.828 g/ml x (?ml/?gal)
Makes sense?

Answer 2

Thank you for your help. I still dont know how to do it. I think I might just leave it like that