# For Those Good In Physics water Level Problem.

1. Aug 12, 2006

### cterence_chow

For Those Good In Physics!!!!!!!!!water Level Problem.

Here's the question.

U are on a boat with a piece of lead on the boat.The water level rose due to more volume of water displaced.So, when we throw the piece of lead into the water,will the water level rise or fall or remain the same in its current water level???:

2. Aug 12, 2006

### mengshuen

i think the water level would fall relative to the boat. the piece of lead is denser than water and hence would not displace as much water to cause the water level to rise to meet the current water level. something that i have learnt just yesterday. :D

3. Aug 12, 2006

### Mk

U? Who's U? It must be a group of people because you said "are."

Assuming the boat has a greater volume than the lead, the water level would go down. The lead displaces more mass inside the boat than if you threw it off, because it sinks.

If you had a small chunk of a neutron star and threw it into the ocean, than it would only displace its volume. If you thew it into a boat (and it didn't go through the boat), then it would displace a bit more.

4. Aug 12, 2006

### cterence_chow

All right man thanks guys, this question has been bugging me for a long time

5. Aug 12, 2006

### desA

How large is the body of water your boat is floating on? A swimming pool, or on a lake?

6. Aug 12, 2006

### cterence_chow

lake.Then??

7. Aug 12, 2006

### cterence_chow

Does the volume of water affect the water level??

8. Aug 12, 2006

### myself

We only need to see how much the volume of water increases. If the lead is in the boat, it displaces water equal to its weight (so it floats). If the lead is in the water, it displaces water equal to its volume (so it sinks). Since lead is denser than water, it displaces more water in the boat than it does when it's in the water. Hence the water level drops when you throw it off the boat. (It is interesting to not that when you are picking up the lead weight to throw it off the boat the water level rises, since there is more downwards force on the boat causing it to displace more water.)

The volume does not affect the water level, but the surface area of the lake/swimmingpool/ocean affects the water level change (change in water level = change in volume / surface area).

9. Aug 12, 2006

### cterence_chow

allright thanx

10. Aug 14, 2006

### vincikai

fall because the total displaced water volume is less than before:rofl: