Added Mass

Let's take a look!

Watch the video on YouTube.

What kind of experiment is this?

Experimental procedure and explanation:

• Float a styrene foam board (such as a food tray) on water, and stab it with a disposable chopstick.
• On a small board, it is difficult to poke a hole through, but on a larger board, it is easy.
• When you strike a board, both the board and the surrounding water are accelerated. Hence, you need enough force to accelerate the board and the water mass. The apparent mass of the board increases. This increase is called the “added mass.”
• With a larger board, the added mass is much larger than that of the smaller board, so the larger board is more difficult to move. This is why you can poke a hole more easily through the larger board.

[Keywords]	added mass
[Reference]	“The Wonders of Flow” Japan Society of Mechanical Engineering, Kodansha Blue Backs pp. 198-203