Can Reviewing Old Physics Problems Improve Understanding?

[redhot209]

Ok so, I was reviewing some of my old physics problems, to understand it better. I have no clue how I did these problems, so I was wondering if anyone can help me?
1. A polar bear of mass 200 kg stands on an ice floe 100 cm thick. What is the minimum area of the floe that will just support the bear in saltwater of specific gravity of 1.03? The specific gravity of ice is 0.98.

The Answer was 4.0m^2

2. Water flows through a horizontal pipe of cross-sectional area 10.0 cm^2 at a pressure of 0.250 atm. the flow rate is 1.00 X10^-3 m^3/s. At a valve, the effective cross-secitonal area of the pipe is reduced to 5.00 cm^2. what is the pressure at the valve?

The Answer was 0.235 atm

3. A hole of radius 1.00 mm occurs in the bottom of a water storage tank that holds water a a depth of 15m. At what rate will water flow out of the hole?

The Answer was 5.4 x 10^5 m^3/s

4. A 1.0-m^3 object floats in water with 20% of it above the waterline. What does the object weigh out of the water?

The Answer was 7,840 N

Sorry, I know this is a lot of work, but it would very helpful thanks!

 

[turin]

Actually, this is about ten minutes worth of work. Any ideas how you would do any of these?