A Person with an Initial Mass Of $70 \mathrm {~kg}$ Climbs a Stairway and Thereby Rises

Short Answer

A person with an initial mass of $70 \mathrm {~kg}$ climbs a stairway and thereby rises $6.0 \mathrm {~m}$ in elevation. By how much does his mass increase by virtue of his increased potential energy? $\left( c = 3.0 \times 10 ^ { 8 } \mathrm {~m} / \mathrm { s } \right)$