A box of tacks weighs 120 grams when full, when half full it weighs 70 grams. How many grams does the box weigh when empty?
see the previous response.
weight is in newtons,not grams. Grams is a unit of mass.
http://www.colorado.edu/physics/2000/periodic_table/mass.html
To solve this problem, we need to determine how much weight is added to the box by the tacks.
First, let's find the weight of the tacks by subtracting the weight of the box when it is half full (70 grams) from the weight when it is full (120 grams):
Weight of tacks = Weight when full - Weight when half full
Weight of tacks = 120 grams - 70 grams
Weight of tacks = 50 grams
Since the weight of the box when it is empty includes the weight of the tacks, we need to subtract the weight of the tacks from the weight of the box when it is half full to find the weight of the box alone:
Weight of box alone = Weight when half full - Weight of tacks
Weight of box alone = 70 grams - 50 grams
Weight of box alone = 20 grams
Therefore, the weight of the box when empty is 20 grams.