What’s the density in g/cm3?

What substance is it?
A)aluminum
B) iron

Anybody wanna ? (picture included? )

Which accurately compares concave and convex lenses?

A14 kg rock starting from rest free falls through a distance of 5.0 m with no air resistance. find the momentum change of the rock caused by its fall and the resulting change in the magnitude of earths velocity. earth mass is 6.0 * 10^24 kg. show your work assuming the rock earth system is closed.