Greg is trying to push a box of books across the floor of his room. the box of books doesn't move because the forces on the box are when his little brother walks in and starts pushing with him, the box begins to slide across the floor. his brother's pushing, combined with his, makes the forces on the box

Greg is trying to push a box of books across the floor of his room. The box of books doesn't move because the forces on the box are ___To Heavy__. When his little brother walks in and starts pushing with him, the box begins to slide across the floor. His brother's pushing, combined with his, makes the forces on the box ___lighter.

I will answer in English.

The weight of the kid is 30kg.

the surface of his sneakers is 150cm^2

and we know that pressure is defined as: P = F/A

where F is force, in this case, F is the weight of the kid, and A is the surface area.

When the kid is using both his legs to stand, the weight is divided equally between both legs, so we have 15kg per leg.

Then the pressure in each foot is:

P = 15kg/150cm^2 = 0.1 kg/cm^2

If he is using only one leg, then all the 30kg are being supported by that leg, then the pressure is:

P = 30kg/150cm^3 = 0.2g/cm^3