PITTSBURGH (KDKA) - If you were to hold something over a scale, its weight would not register.

Obviously, you have to set something on the scale for its weight to register, but I am just setting up our next experiment.

If something is suspended in the air or floating on water it obviously still has weight and mass, but as mentioned, you need to rest it on the scale to get the weight to register.

Now what if you have a glass of water on a scale and you dip a sinker into the water, but do not let it touch the bottom of the glass?

The weight, even though it does not touch the bottom of the glass and is still supported by the thread does register on the scale.

Even though it is being held up by the thread, our weight is also displacing water in the glass, and the weight changes by how much water is displaced. You can see the water level goes up when the weight is suspended in the fluid, so the scale is reading the difference of how much liquid the liquid "goes up".

The weight read on the scale is not necessarily the weight of our rubber stoppers. They weigh 0.8 ounces. When you are suspending the weight on the string in water, the weight has a downward force, but there is still a buoyant force on the sinker, meaning the water is still pushing it up to some extent. This is why the weight registering on the scale is lighter than the actual 0.8 ounces the rubber stoppers weigh. Once they hit the bottom of the glass, though, their true weight shows up on the scale.

Now you know the science behind why things seem lighter in a swimming pool...Or is it that you feel stronger in a swimming pool?

Meteorologist Ray Petelin joined the KDKA Weather Team in October 2018, but is no stranger to the weather in Pittsburgh and Western Pennsylvania. He has been forecasting in Pittsburgh since 2011 and in Western PA since January of 2003.

First published on May 7, 2022 / 7:52 AM

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©2022 CBS Broadcasting Inc. All Rights Reserved.