How much does one penny weigh?
United States pennies minted after 1982 weigh 2.5 grams, or 0.088 ounces. These pennies are 2.5 percent copper and 97.5 percent zinc. Before 1982, pennies weighed 3.11 grams, or 0.110 ounces. They were 95 percent copper and 5 percent zinc, which is a form of bronze. During 1982, the U.S. Mint issued pennies of both compositions, and both 2.5-gram and 3.11-gram pennies can be found in circulation. The weight of the penny also changed in 1943. Because of a scarcity of copper, pennies were minted from zinc-coated steel. These weighed 2.7 grams, or 0.095 ounces. Other small changes in design and metal composition have been made over the last hundred years, but they have not changed the weight of the coin except as already described.
What are your thoughts on this subject?
7 Comments
Duncan Evans
Richard, I also do not usually take time to comment on sites like this, but I'll make an exception here.
Mass and weight are two different concepts. Mass deals with how much matter an object contains. Weight deals with the force exerted by that mass due to the gravity where it is measured. Weight will change, if it is measured in a place that has a different force of gravity, such as on the moon. Mass will remain constant no matter where it is measured.
In the metric system, MASS is measured by grams (kilo-, etc). This a representation of how much matter the object contains. A penny masses 2.5 grams, whether it is on the surface of the Earth, or on the moon. Because we common folk do not often have to deal with how much an object weights on the moon, we often incorrectly use the measurement of mass to refer to weight in the metric system. The fact that grams are commonly used as a measure of weight DOES NOT make it correct. The correct unit in the metric system for weight is the Newton. On Earth, 1 kg is equivalent to 9.8 Newtons. A 200 kg man, on the surface of the Earth, weighs 1960 Newtons. The same 200 kg man, on the moon, would only weigh about 342 Newtons, due to the lower gravity, but he would still contain the same amount of matter, and would therefore still mass 200 kg.
In the imperial system, the standard unit for weight is the pound (lbs). We do have a unit for mass, however. It is called the SLUG. (The resemblance of the name to a shell-less snail is probably part of the reason that it is not more often used.) On the surface of the Earth, one slug is equivalent to 32.174 lbs. So a man that weighs 200 lbs on Earth has a mass of 6.216 slugs. On the Moon, he will only weigh around 33 lbs., but he will still mass 6.216 slugs.
So technically, you cannot 'weigh' anything in grams. You can determine its mass in grams, and its weight in Newtons. Which is the point Andrew was making. He could have given a more detailed explanation, true, but he was not incorrect.
Charlotte Knight
I don't see where the article says otherwise. Did I miss something?
Richard Pfifferling
Andrew, I do not usually take time to comment on this light and entertaining site... and especially to reply to another person's post.
However, I noticed you went to the trouble to highlight "Rutgers University."
It would be startling, and a bit discouraging, to think a University student does not know what a gram is. OK, now multiply that by ten, since you also do not seem to know how to look up in a book, or Google, a simple definition before you spout off.
Andrew.. for your information, a gram is a unit of measure. Yes, you can even measure the weight of American coins using the metric system! Amazing! Now go have a nice cool liter of water and calm down.
Jonathan Hill
Anything solid " such as a penny " can be weighed in grams. Get your facts straight
Jonathan Hill
Anything solid " such as a penny " can be weighed in grams. Get your facts straight
Andrew Williams
Actually it does not "weigh" grams, grams are a metric unit and describe the mass of something, not how heavy it is -.- get your facts straight
Andrew Williams
Actually it does not "weigh" grams, grams are a metric unit and describe the mass of something, not how heavy it is -.- get your facts straight