You can separate sand into many different substances by pouring it through a filter. what is sand?

Glass has a hardness that is in the middle of the hardness scale. what is the hardness of glass?

Atank has a shape of a cone with a radius at the top of 2 m and a height of 5 m. the tank also has a 1 m spout at the top of the tank. the tank is filled with water up to a height of 2 m. find the work needed to pump all the water out the top of the spout. (use 9.8 m/s2 for g and the fact that the density of water is 1000 kg/m3.)

What does the law of conservation of mass state?