The box of a well-known breakfast cereal states that one ounce of the cereal contains 113 Calories (1 food Calorie = 4186 J). If

Question

2 years ago

12

The box of a well-known breakfast cereal states that one ounce of the cereal contains 113 Calories (1 food Calorie = 4186 J). If

1.79% 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 1.90 m?

Physics

2 answers:

zimovet [89] · Answer 1 · 2022-03-21T01:05:29+03:00

Answer:

4456.33N

Explanation:

Let the energy converted by the lifter's body into work done be E.

The work done in lifting the barbell is against gravity and it is given by equation (1);

$work done=mgh..................(1)$

where m is the mass of the barbell, g is acceleration due to gravity and h is the vertical distance (height) through which it is lifted. Hence by the principle of energy conversion as specified by the problem we could write the following equation;

$E=mgh.....................(2)$

Also, it should be recalled that the weight, W of an object is given by the equation below;

$W=mg...............(3)$

Substituting (3) into (2) we obtain the following;

$E=Wh..................(4)$

Given; h = 1.9m

To obtain the energy E converted by the lifter's body in Joules, we use the specifications given in the problem as follows;

Given; 1cal = 4186J

therefore 113cal = (113 x 4186)J = 473018J. This is the total energy contained in one ounce of cereal consumed by the lifter. However as specified by the problem, only 1.79% of this energy was converted by the lifter's body into weight lifting, therefore;

$E=\frac{1.79}{100}*473018J=8467.02J$