Question

Duncan knows that it takes 36400 cal of energy to heat a pint of water from room temperature to boiling. However, Duncan has prepared ramen noodles so many times he does not need to measure the water carefully. If he happens to heat 0.600 pint of room-temperature water, how many kilojoules of heat energy will have been absorbed by the water at the moment it begins to boil?

Answer 1

This is a problem of direct proportion and unit conversion

36400 cal / 1 pint = x / 0.600 pint => x = 0.600 pint * 36400 cal / pint = 21840 cal

Conversion factor: 1000 cal = 4.184 kJ

21840 cal * 4.184kJ / 1000 cal = 91.379 kJ

Answer: 91.379 kJ