Grantham University
Physics I
Week 7 Assignment

Week-7 Assignment
Temperature, Kinetic Theory, and Sound 1. A diamond has a mass of 56.6 g and the gold ring it is set in has a mass of 125.6 g. How many carbon atoms are there compared to gold atoms?
# of carbon atoms=6*1023*56.6/12
=2.83*1024 atoms
# of gold atoms=6*1023*125.6/197
=3.825*1023 atoms 2. On a warm summer day in California it can get as hot as 115oF, and on some cold winter days it can get as cold as -20oF. What are these temperatures in Celsius?
Celsius=(F-32) * 5/9
C=(115-32) * 5/9 =46.11C
C2=(-20-32) * 5/9 =-28.89 C 3. An aluminum sphere is 5.50 cm in radius. What is its volume expansion coefficient if it increases in volume 2.00 cm3 when heated from 100 oC to 151 oC? (4/3)*π*5.53*x*(151-150)=2 x=2.87*10-3 4. Carbon 12 is defined such that 12g is one mole. So if a diamond is 37.5 g, how many moles of carbon are in it? How many molecules of carbon are in it?
1 mole = 12 grams moles of carbon=37.5/12
=3.125 moles

5. 400 L of water is at 4 oC. If it took a heat 600 seconds to heat this up to 6 oC, what is the power rating of the heater?
=400 * 4180 * (6-4)/600
=5.57 kW 6. A 95g cup of tea at 85 oC is poured into a 1.25 L large tub of water at 30 oC . What is the equilibrium temperature?
=95*4.18*(85-t)
=1250*4.18*(t-30) t=33.88 C 7. 150 g of ice at -10.5 oC is raised to the melting point and then raised to 76.0 oC. How much heat is added to the system?
It takes 4.186 Joules to heat one gram of water by 1-degree Celsius.
=150*334 + 150*2.1*10.5 + 76*4.18*150 heat is added to the system =101,060J 8. A distant star is 7000 K and radiates 1.20 x1027 W. What is the star’s radius? Assume ε = 1.0. sigma*A*e*T4=P 5.67*10-8*4*π*r2*1*(70004) = 1.2*1027
r=8.375