Need help with these three questions.

[wolfskymoon]

Got a take home exam. Has 100 questions and i'm allowed to get help. Problem is i studied all year, but i still am having trouble even figuring out what formulas to use for these few questions i still have left. Was wondering if someone could point me in the right direction, don't exactly have to solve them for me.
^ = Power. I don't know how to type it small on top of the number

1- Use the following values for moment of inertia:-
Cross-Arm apparatus: I= 2.32 x 10 ^ -3 kg.m^2 and drum diameter 4.04cm
Disk: M= 4.505kg and diameter 24.0 cm
Ring: M= 4.505kg diameters 23.0 cm and 24.0 cm
Assume an initial height of the accelerating mass of 1.40 m and take the accelerating mass to be 1000 grams. Calculate the final velocity of the accelerating mass (just before it hits the floor) if both the disk and the ring ride on the cross-arm apparatus.



2- A quantity of water at 10 degree C is being used to cool the copper heat sink attached to the CPU of a computer. Assume that (because the computer is being used to decode the hdtv broadcast) the initial temperature of the heat sink is 65 degree C. Further assume that all the water is continuously in contact with the heat sink. If the mass of the heat sink is 255 grams, compute the mass of water necessary to reduce its temperature at 28 degree C.


3-An air bubble of volume 1.75cm^3 is erleased from a submarine at a depth of 300m in the ocean where the temperature is 5 degree C. Assuming that sea water has a density of 1030 kilograms per cubic meter and that the pressure at the surface of the ocean is 1 atmosphere (1.013 x 10^5 Pa), and that the temperature at the surface is 8 degree C, find the volume of the bubble when it reaches the surface.
These three are giving me trouble. If i get help with these, i'm down to help with AF quests and such or w/e in return =).

 

[smalls]

pretty sure this is how to do number 2:

q= m * c * delta T
q is energy, m is mass, c is specific heat, delta T is change in temp.

since the energy lost by the copper is equal to the energy gained by the water you can set them equal to eachother.
copper specific heat = .385, water = 4.179

(255g) * (.385) * (65-28) = (???g) * (4.179) * (28-10)

then just solve for the unknown

 

[wolfskymoon]

I love you man. Hit me up if u need anything in FFXI =0.

 

[wolfskymoon]

Three more physics questions (Last)

K i only got 3 out of 50 left to solve now. Any kind of pointers would be greatly appreciated.
4- Due to solar and lunar tidal forces, the Earth's rotation is experiencing an angular acceleration of -6.5 x 10 ^ -22 rad/s^2. As a result, while the day is currently 24 hours long, it has been different in the distant past, and will be different in the future. Assuming that this angular acceleration is, was and will be contant with respect to time, calculate thow many years from now th elength of a day was(or will be) 22 hours, and tell wheather the 22 hour day is a thing of the past, or a future occurence.



5- A metal coin of mass 31.1 grams is heated using a torch which supplies 100 calories of heat to it. If the temperature of the metal goes from 19.0 degree centigrade to 122.4 degree centigrade, find the specific heat of the metal and speculate on what metal that coin is likely to be made of.

6- Assume that the solar system consists only of the sun (mass = 1.991 x 10 ^30 kg), jupiter(mass = 1.90 x 10 ^ 27 kg), saturn (Mass = 5.68 x 10^26kg), Uranus (mass = 8.68 x 10 ^ 25 kg), and Neptune (Mass = 1.03 x 10^26 kg). Further assume that all the planets move counterclock wise in circular orbits cenetered on the Sun. Take the origin to be at the center of the Sun and the radial distances and angles of the planets in that coardinate system are as follows (with all angels measured counterclockwise from X-axis):

Planet Distance from Origin Angle Time for one orbit.
Jupitar 5.197 AU 283 11.857 years
Saturn 9.303 AU 158 29.424 Years
Uranus 20.10 AU 349 83.747 years
Neptune 30.04 AU 322 162.72 years
Where 1 AU = 1.496 x 10^11 m
a- Find the x and y coardinates of the center of mass of the solar system
b-Find the orbital angular momentum of each planet and add all four to get the total angular momentum of the solar system.
c- Find the orbital kinetic energy of each planet and the total orbital angular momentum of the solar system as a whole.








I know how to do 5 now. But 4 and 6 are still tough..