How are volume and displacement alike

Put a block of lead in water and the volume of the lead will displace that volume of water. The same cannot be said with mass as they have different densities (different weight for the same sized thing). Hopefully this helps

the last statement is correct i.e.

the artificial heart has limited usefulness but can prolong life or be a tool to use while waiting for a transplant.

when your heart is not pumping enough blood around your body because your heart is severely failing, you may need an artificial heart. an artificial heart is a mechanical device, about the size of an orange, that is connected to your heart or implanted in your chest to or replace a failing heart.

Well if you pick a machine to work on and that's gonna be your exercise if you don't stick to that machine your muscle strength your muscle mass rather will change because you haven't been doing it you change something in your exercise routine which changes your body's form of dealing with things for example you might become weaker or stronger depending on what kind of exercises you do in whether or not the machine you picked actually your muscles grow.