how do we measure the weight & mass of a balloon filled with helium?

Question

My intuition leads me to believe that the balloon would have negative weight? and I have no idea how we could measure the mass

In: 2

Answer 1

The balloon still has a positive weight, it just has less weight than an equal volume of the air around it.

I can’t think of a “easy” lay-person way to measure the weight of a helium filled balloon that doesn’t involve at least basic chemistry.

The easiest form would be use buoyancy and a [spring scale](https://www.dscbalances.com/products/ohaus-8001-mn-spring-scales-scale?variant=36823588765846&currency=USD&utm_medium=product_sync&utm_source=google&utm_content=sag_organic&utm_campaign=sag_organic&utm_source=google&utm_medium=cpc&utm_campaign=shopping+-ohaus-scales&utm_term=&hsa_tgt=pla-1098142444058&hsa_kw=&hsa_mt=&hsa_ver=3&hsa_net=adwords&hsa_ad=489046553941&hsa_acc=8236532222&hsa_cam=1471685992&hsa_grp=118712596231&hsa_src=g&gclid=Cj0KCQjwyOuYBhCGARIsAIdGQRNXDZPNxkZLQrc8gmg6roaWtCHc312EUcF2-KvsPjtJqdSK_KQG_IgaAlb-EALw_wcB).

A spring scale is like what they used to use to measure the weight of vegetables in a grocery store, it’s a spring that’s attached to a spinning dial that translates the force pulling on the spring into a weight reading on the dial.

If you attach the balloon to the spring scale you can measure the buoyancy (the upwards pulling force) of the balloon.

That force is directly related to the volume of gas (a measurement of space) inside the balloon and the density of the helium (a measurement of weight divided by space).

So it’s math, but trivial math to calculate the weight of the helium if know the volume of the balloon, the density of the helium (usually easy enough to look up in a text book in 99% of contexts) and the reading from the spring scale.