If you fully submerge an object, you displace its VOLUME of water. It will always be the same amount (imagine a bowling ball and a soccer ball). You might need to push it.
When you relate that to its weight, you get the density.
Interestingly, when an object floats you can weigh it, because it will displace as much mass of the liquid it floats in as it weighs itself. You can’t get the density that way.
Imagine you have two 1kg lumps of steel. Out of one you make a bowl with thin walls the out of the other a metal ball. Afterwards they still have (about) the same weight, volume and density - as it’s still steel.
But put the bowl onto the basin and with a little luck it will float like a boat, put in the steel ball it will sink.
But when you put in the bowl sideways without splashing it will displace about the same amount of water than the ball. And it will still weigh 1kg.
If you fully submerge an object, you displace its VOLUME of water. It will always be the same amount (imagine a bowling ball and a soccer ball). You might need to push it.
When you relate that to its weight, you get the density.
Interestingly, when an object floats you can weigh it, because it will displace as much mass of the liquid it floats in as it weighs itself. You can’t get the density that way.
Imagine you have two 1kg lumps of steel. Out of one you make a bowl with thin walls the out of the other a metal ball. Afterwards they still have (about) the same weight, volume and density - as it’s still steel.
But put the bowl onto the basin and with a little luck it will float like a boat, put in the steel ball it will sink.
But when you put in the bowl sideways without splashing it will displace about the same amount of water than the ball. And it will still weigh 1kg.