Question

Hi im doing measurement at skool at the moment and i cant quite ork out some questions. Can someone please help!!

A metal washer has an external diameter of 2cm and an internal diameter of 1cm.

A) How many washers can be cut from a sheet of steel 3m by 1m?

B)If the metal left over was remelted and cast into a sheet of the same thickness and width 1m, how many additional washers could be cut?

Answer 1

A) If the washers are cut in a square array, you can get 100/2 = 50 per mm for a total of 150 x 50 or 7500 washers. You can get even more with a hexagonal close packed array. (Try it with pennies). In this case. the distance between rows is D*(sqrt3)/2 = 1.732 cm and you can get 57.7 rows per m, or 173 rows in 3 meters with alternately 50 or 49 per m, for a total ofN = 173 x 49.5 or 8563.

B) Calculate the volume of N washers (not counting the holes!) and divide that into the volume of the sheet of steel.