What is the concept behind the coin and the boat?

Question

..... you know.... why the boat floats and the coin does not.....

Answer 1

density. also the air in the hollow space of the boat

Answer 2

The boat displaces water equal to it's weight. The displaced water tries to flow back and exerts pressure on the boat. You can make a small hole in the boat to check for pressure. Water will squirt in. Provided a little extra boat sticks out above the water it will float. If you put more weight in it, it will displace a bit more water (read up on plimsoll lines). A coin does not displace enough water to equal it's weight (unless it is a wooden coin) so it sinks. A very small and thin coin could stay on the surface due to surface tension if placed there carefully but it is not actually floating.

Answer 3

the boat is more bouyant than the coin