Can a covex lens be transparent glass

An object has a weight of 500 on earth what is the mass of this object

A1-lb collar is attached to a spring and slides without friction along a circular rod in a vertical plane. the spring has an undeformed length of 5 in. and a constant k =25 lb/ft. knowing that the collar is released from being held at a determine, the speed of the collar and the normal force between the collar and the rod as the collar passes through b.

Give one example to show that when substances are mixed,it may result in a chemical or a physical change depending on the conditions.