The box of a well-known breakfast cereal states that one ounce of the cereal contains 129 Calories (1 food Calorie = 4186 J). If 2.55% of this energy could be converted by a weight lifter's body into work done in lifting a barbell, what is the weight of the heaviest barbell that could be lifted a distance of 1.91 m?

Answer 1

129 Cal * 4186 J/Cal = 536,124 Joules

.0255 * 536,124 = 13,671 Joules

m g h = m g (1.91) = 13,671

so

m g = 7158 Newtons weight

and
m = 730 Kilograms of mass

around 1600 pounds