Un niño de 30kg está usando zapatillas, cada una con una superficie de apoyo de 150cm2 . Calcula su peso y la presión cuando está apoyado con los dos pies y cuanto está apoyado en un solo pie.

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

where is the