An energy bar contains 4 g of fat, 12 g of protein, and 24 g of carbohydrates. How many kilojoules of energy are obtained from eating two bars per day for a month? Write the answer in scientific notation.

Given, Mass of Fat = 4g (mf)

Mass of Protein = 12g (mp)

Mass of carbs = 24 g (mc)

First we need to determine energy obtained from eating an energy bar :

E = mf.ef + mp.ep + mc.ec

Where as ef = the energy of fats per unit mass (39.8kJ/g)

ep = energy of proteins per unit mass (22.2 kJ/g)

ec = energy of carbohydrates per unit mass (18.0 kJ/g)

Substitute above values in formula

---- > (4)(39.8) + (12)(22.2) + (24)(18.0) = 857.6 Kj

Now, determine the total energy obtained by

consuming 2 energy bars per day, for 30 days:

--- > E total = ( 857.6 / bar ) × (2 bar/d) × 30d =

51 × 10³ KJ