10. Question 10 [10 marks total] a. In your own words, describe the difference between elastic deformation and plastic deformation. [2] The stress-strain curve for a material is shown below. 2000 1800 1600 1400 1200 1000 800 600 400 200 0 0 0.02 0.04 0.06 Strain Stress (MPa) The sample has a diameter of 0.8 mm (0.8 x 10'3 m) and an initial length of 0.500 m. In the questions below. assume that a fresh sample is being used each time. b. Determine the length of the sample when a tensile force of 400 N is applied. [3] 0. Determine the length of the sample when a tensile force of 900 N is applied. [2] d. Determine the length of the sample at the fracture stress. [3] PAGE11OF11 4. Question 4 [10 marks total] A cross-section of a building wall is shown betow. The thickness of the wall is 20 cm. The inside of the buiEding is kept at a temperature of 25 0C. When the outside temperature is 2 \"C, the heat flux through the wall is 138 W m"? The wall is made from Material X. Material X is one of the materials listed in the table below. M te ial Thermal conductivity, 3 r k (w m-1 K\") q" = 138 W or2 Brass 110 TInsnde = 25 ac Toulside = 2 0C Steel 50 Super alloy 12 Stone 4.0 Concrete 1.2 Material X 20 cm Wood 0.2 a. Assuming steady-state conditions, calculate the thermal conductivity of the wall, and state the identity of Material X. [3] A different room has a wall that is made from two layers. Layer 1 is 10 cm thick and made from wood, layer 2 is 20 cm thick and made from stone. A simplified cross-section of the wall is shown below. The inside temperature is 25 \"C. and the outside temperature is 2 \"C. q}! TInsrde = 25 0C ToutSIde = 2 ac (>(> Wood Stone 10 cm 20 cm b. Assuming steady-state conditions, calculate the heat flux through the wall. [7] PAGE 5 OF 11 2. Question 2 [10 marks total] The ideal gas law and the van der Waafs equation are shown below: Idea! gas law: PV : nRT van der Waals equation: '9'\" : anZb _ a ($2 a) State the two main assumptions made about ideal gases. [2] There are two samples of the same gas: sample A and sample B. Both samples contain 2 moles of gas and have a volume of 0.01 m3 but have different temperatures and pressures. The ideal pressure (Pldeal) calculated using the ideal gas law is included in the table below. n (mol) V (m3) T (K) Pideal (Pa) Preal (Pa) Sample A 2 0.01 400 665120 ? Sample B 2 0.01 100 166280 ? b) Calculate the Pm. of each sample (a = 0.3? Pa mE moi\8. Question 8 [10 marks total] A mercury thermometer displays a linear relationship between temperature and height of mercury about the thermometer bulb. The thermometer is calibrated using two points: - When the thermometer is placed in a solution at 10 C, the height of the mercury above the bulb is 12 mm. - When the thermometer is placed in a solution at 160 GTB, the height of the mercury above the bulb is 136 mm. When the thermometer is placed in a solution at a different temperature, the height of the mercury above the bulb is 118 mm. a. Calculate the temperature of the solution when the height of the mercury above the bulb is 118 mm. [5] At 25 C, a block of steel is constrained so that its length cannot change. At 25 CC, there is no stress within the block. b. If the block is heated to the same temperature that you found in part (a), will the block break? Show calculations that support your answer. [5] Gsieel = 18 x 10'500'1, E = 200 GF'a, Gmax = 200 MPa PAGE 9 OF 11 6. Question 6 [10 marks total] a. Explain in your own words what specific heat capacity is. [2] A well-insulated calorimeter contains 200 g of water at a temperature of 5 .C. A 75 g block of an "AlBeMet" alloy at a temperature of 300 C is added to the calorimeter. The system is allowed to reach thermal equilibrium. (Cwater = 4.18 J g-1 .C-1, Calloy = 1.51 J g-1 .C-1) b. Calculate the final temperature of the alloy and water. [4] In a separate experiment, a well-insulated calorimeter contains 200 g of water at a temperature of 5 .C. To the calorimeter, 75 g of the "AlBeMet" alloy and an unknown mass of gold are added. Both the alloy and the gold have an initial temperature of 300 C. The system is allowed to reach thermal equilibrium. The final temperature is 46 .C. (Cgold = 0.13 J g-1 .C-1) c. Calculate the mass of gold added to the calorimeter. [4] PAGE 7 OF 11