Grammar/ Spelling check, please!?
My hypothesis is that a penny will have slightly less mass if it is older. I think so because items tend to wear down as they age. If a penny wears down, it's mass will decrease.
Age does not affect the mass of penny.
I think that the older and new coins may be made of different metals which would affect their mass.
All coins probably will be affected the same way a penny will be. I think that age will have little effect on the mass of a nickel, dime, or quarter.
My histogram shows that there were a few stray pennies amongst the most popular masses, 2.5 g and 3.1 g. It also identified the two main masses.
In 1982 the penny's composition was changed. The penny changed from being made from 95% copper and 5% zinc to about 98% zinc and 2% copper. This switch of materials changed the mass of the penny.
Older pennies tend to have a greater mass then newer ones.
All coins probably will be affected the same way a penny will be. I think that age will have little effect on the mass of a nickel, dime, or quarter unless their components have been changed.