(adsbygoogle = window.adsbygoogle || []).push({}); Thermal Energy/ States of Matter- Help!!

Hey guys! I have been on the road traveling for 6 weeks straight with not much time for schoolwork. Now I am home for 4 days so I have to get to work. I have finished one of my physics tests but wanted some reassurance that the answers are correct- as I cannot afford a bad grade- must keep the grades up. I will post the problems and my solutions and if you could check over them that would be greatly appreciated! Thanks ahead of time!!!!!

1) Which takes less time to melt, one Kg of ice, one Kg of lead, one Kg of copper, or one Kg of silver? Assume that ea h solid is at its melting point and the heat energy is being applied to each solid at the same rate.

I beleieve that the answer to this one is silver because it has the lowest heat of vaporization at 1.04 x 10^4.

2) Container A has 50 Kg of water in it. container B has 30 Kg of water in it. If both containers have equal quantities of heat energy then__________.

I beleieve that container B and its contents would have a higher temperature than conatiner A due to the fact that there is less material within it. Is this right??

3) If the density of mercury is 13.59 x 10^3 kg/m^3 at 20 * C, what will its density be at 65 * C?

OK...this is where I am confused. I believe that you somehow have to incorporate the equation Vi(coefficient of volume expansion)(change in temperature)= m^3....so you would use 13.59 x 10^3 (180 x 10^-6)(65*-20*). Does this sound correct? I got the answer to be 675 N but that doesn't seem correct....

4) In a certain hrdraulic liff, the small piston has a radius of 15 cm. The large piston has a radis of 26 cm. A force of 225 N is applied to the small piston. What is the mass of the crate that is being lited by the application of this 225 N force?

Here I know that you have to use Pascal's principle and the equations P1= F1/A1...(pressure= force/surface area)and F1/A1=F2/A2....I don't understand this enough to solve it...

5) The heat of vaporization of mercury is 2.72 x 10^5 J/Kg. How many grams of mercury at its boiling point can be vaporized by the addition of 4.53 kJ of heat energy?

Here, I think you would use Q=m(Hv)

4530 J= m(2,72 x 10^5)

m= .01665 kg or 16.7 g

Thank you so much for your time- I really appreciate it!!!

**Physics Forums | Science Articles, Homework Help, Discussion**

Join Physics Forums Today!

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

# Homework Help: Thermal Energy/ States of Matter- Help

**Physics Forums | Science Articles, Homework Help, Discussion**