Physics Van 3-site Navigational Menu

Physics Van Navigational Menu

Q & A: Does BS weigh less once it's spread?

Learn more physics!

Most recent answer: 10/31/2011
Q:
We're having this physics discussion at work (in the medical field). One of my co-workers insists that if you took a pound of anything and spread it out evenly on a scale, it would weigh less than if you piled it up in the middle of the scale. He said that the density of the mass of whatever you piled on the scale, would increase the gravitational pull moreso than if the object being weighed was spread out evenly, like say mashed potatoes, for example. What do you say? Thanks, Tara Lynne Myers
- Tara Lynne Myers (age 50)
Richland, Pennsylvania
A:
I say you should offer a little wager to your co-worker. (He's Chief of Surgery, I presume?) Just be sure to use a good lab scale. Cheap spring scales often read a little higher or lower depending on how the weight is distributed on their surface, and you wouldn't want to introduce any element of chance into this financial transaction.

Mike W.

(published on 10/30/2011)

Follow-Up #1: weight and distribution

Q:
I assume your answer would be that a pound weighs a pound, no matter how it is distributed on the scale. Am I correct? No, this man is certainly not a doctor or surgeon. He's a Telemetry Monitor Technician. I am a Nurse. I am not someone who wastes money betting. I love to do research, and I see where Newton states that W=mg (Weight equals Mass + Gravitational Acceleration. Is this the relevant formula I would be referring to? Thanks! Tara
- Tara Lynne Myers (age 50)
Richland, Pennsylvania
A:
Yes, correct. Certainly that's the relevant formula, although that should be an "x" (times) not a "+" in the verbal version.

Sorry for kidding around about the wager.  The real point is that it's straightforward to test this with any decent lab scale. The results, however, are not in doubt.


Mike W.

(published on 10/31/2011)

Follow-up on this answer.