Calculate the momentum of a man of mass $75 \mathrm{kg}$ when he walks with a uniform velocity of $2 \mathrm{m} {\mathrm{s}}^{-1}$.

There are two types of forces $\mathrm{X}$ and $\mathrm{}\mathrm{Y}$. The forces belonging to type $\mathrm{X}$ can produce motion in a stationary object but cannot change the shape of the object. On the other hand, forces belonging to type $\mathrm{Y}\mathrm{}$ cannot produce motion in a stationary object but can change the shape of the object. What is the general name of the forces such as $\mathrm{X}$?

(Choose from: Balanced forces / Unbalanced forces)