A 1500kg rollercoaster car is moving at 4.5m/s at the top of a 30.0m hill. Assuming no energy is lost to friction, how fast will they be moving when they have travelled down the hill to a new height of 12.5m?

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).