RESULTS: Table 1: Brinell Hardness Tests Results Test Material Aluminum Brass Mild steel Nylon Maximum Force (N) Dent Diameter (mm) Indenter Diameter (mm) 10 10 10 10 Test time (sec) 15 15 15 15 BHN Table 2: Hardness Conversions Aluminum Brass Mild steel Nylon BHN [Experimental value] Rockwell B Hardness Rockwell C Hardness Vickers Hardness Knoop Hardness NALYSIS: Calculate the BHN for all materials. Fill the results in table 1. Show the detail calculation of BHN for one material only.

An electric hot water heater consumes 3.1 kilowatts of electricity and converts it to heat. How long will it take the water heater to heat a 67 gallon tank of water from 10 degrees Celsius to 50 degrees Celsius? (1 kilogram of water is 0.37 gallons, 1 Calorie = 4200 J).  It may be helpful to refer back to the weekly handout for guidance on this problem. Your final answer should be in minutes (rounded to the nearest 10 minutes).

There may or may not be one or more mistakes in the solution. Go through the solution carefully and then do the following. 1. State if the solution is correct or incorrect 2. If the solution is incorrect, identify what is the mistake in the solution. Be specific and succinct. 3. If the solution is incorrect, provide the final solution with appropriate steps. Problem: A refrigeration cycle uses refrigerant R-134a to cool down water from 40°C to 20°C. The refrigerant R-134a enters the cycle as saturated liquid at -15°C and exits as saturated vapor at the same temperature. The mass flow rate of R-134a is 0.12 kg/s. The overall heat transfer coefficient is 1400 W/m².K. The surface area of the heat exchanger is 1.4 m². What is the rate at which heat is being exchanged between R-134a and water? Assume that the heat exchanger is perfectly insulated from outside (i.e., there is no convection or radiation with the outside/surrounding). Solution: We know, from the definition of overall heat…

When does force work?