Is it possible to float a car on water using either aerogel or fiberglass or something like that?
Anything can float under the right conditions. All we need is W = B; where W is the weight of the anything and B is the buoyancy force of the thing in the liquid. That is, anything will float so long as the amount of fluid it displaces weighs what the floating thing weighs. So the weight of the car is Mg = W, where M is the car’s mass and g is acceleration due to gravity. The car with volume of v will float if it displaces a volume V of liquid that weighs B as much as the car does, which is W. B = rho g V; where rho is the mass density of the liquid and g is the same g as before. Thus when W = mg = Rho v g = rho V g = B, your car will float. Rho is the mass density of the car. Thus, we have V = (Rho/rho)v from above. In other words, your car will float if and only if the volume of displaced liquid is greater than the volume of the car by a factor of (Rho/rho). But wait, v < V is the volume of the car. So how can it displace V amount of liquid, which is bigger than v? That brings us to
