Weather balloons are filled with only a small amount of helium because the of the balloon will increase as the air pressure decreases at higher altitudes.

What is the coefficient of kinetic friction μk between the block and the tabletop?

Which planet do you think would be easiest for humans to colonize some day?

Ahypothetical metal has an orthorhombic unit cell for which the a, b, and c lattice parameters are 0.413 nm, 0.665 nm, and 0.876 nm, respectively. (a) if there are 8 atoms per unit cell and the atomic packing factor is 0.536, determine the atomic radius (in nm). (b) if the density is 3.99 g/cm3, calculate the metal's atomic weight (in g/mol).