Concept explainers
We go out to sunbathe on a warm summer day. If we soak up 100 British thermal units per hour [BTU/h] of energy, how much will the temperature of 132 pound-mass [lbm] person increase in 2 hours [h] in units of degrees Celsius [°C]? We assume that since our bodies are mostly water they have the same specific heat as water, 4.18 joules per gram degree Celsius [J/(g °C)].
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- T1- Ambient tempeture [k] t- inside tempeture [k] hoo-convective heat transfer coefficient of the air [W/m^2*k] t-thickness of walls[m] Kthermal conductivity (W/m-K) -(VIP) d-cube size [m] Ai-cube area inside [m^2] Ao-cube area outside [m^2] Ts-surface tempeture[k][ E-emissivity aluminium foil - Stefan Boltzmann constant W·m-2 K-4 303 290 10 0.08 0.007 1 6 6.96 300 0.03 5.67E-08 Q heat flux [W] ΔΤ ΣR F T₁ 111.0 0000 006%arrow_forwardAn insulated, constant-volume system containing 1.36 kg of air receives 53 kJ of paddle work. The initial temperature is 27 C. Determine (a) the final temperature [1 decimal place] and (b) the change of internal energy [whole number].arrow_forwardA vertical piston-cylinder arrangement with a diameter of 120 mm contains water with a quality of 60%. The pressure is 3 bar. Initially the piston rests 40 mm above the bottom of the cylinder. Heat is then added until the volume is 3 times the original volume. (a) Determine the mass of the water in the cylinder [ Select ] O kg (b) Determine the work done. [ Select ] O (J) (c) The final temperature [ Select ] O °C (d) The heat transferred to the system [ Select ]arrow_forward
- To heat potatoes, you use a microwave with an output power of 780 watts [W]. The microwave has "pre-set" cook buttons. The "potato" button will cook a 0.625 pound-mass [lbm] potato by heating the potato from room temperature (assumed to be 68 degrees Fahrenheit [°F]) to 425 degrees Fahrenheit [°F]. The specific heat of a potato is 3.4 kilojoules per kilogram kelvin [kJ/(kg K)]. What is the length of time the "pre-set" button is programmed to operate in units of minutes [min]?arrow_forward2. Complete the blank cells in the following table of properties of steam. In the last column describe the condition of steam as compressed liquid, saturated mixture, superheated vapor, or insufficient information; and, if applicable, give the quality. P[kPa] T[°C] v[m³/kg] а. 500 20 b. 500 0.20 с. 1400 200 d. 300 0.8arrow_forwardComplete the following Table for water. For each case, draw a separate T-v diagram and qualitatively mark each thermodynamic state on the diagram. Show all required calculations for full credit. p[kPa] T[°C] v [m³/kg] u [kJ/kg] X state h [kJ/kg] 2260 275 400 700 350 1 2000 20arrow_forward
- When not in use, the water in a pool is kept at a temperature of 60 degrees Fahrenheit [°F]. For synchronized swimming competitions, the water should be increased by 18 degrees Fahrenheit [°F]. The system that heats the water can raise the temperature of the water by 3.4 kelvin [K] every 13 minutes [min]. Determine the time it will take to heat the pool to the appropriate competition temperature in units of hours [h]. Click the icon to view the factors for temperature intervals conversion. The time is h. (Round your answer to two decimal places.)arrow_forwardWater enters a boiler at 20 degrees Celsius [°C]. The boiler operates for 5 minutes [min] to heat 25 gallons [gal] of water. The boiler requires an input power of 15.5 kilowatts [kW] and is 85% efficient. The specific heat capacity of water is 4.18 kilojoules per kilogram kelvin [kJ /(kg K)]. What is the temperature of the water in degrees Celsius [°C] as it exits the boiler?arrow_forwardA robotic rover on Mars finds a spherical rock with a diameter of 8 centimeters [cm]. The rover picks up the rock and lifts it 25 centimeters [cm] straight up. The rock has a specific gravity of 4.75. The gravitational acceleration on Mars is 3.7 meters per second squared [m/s²]. If the robot's lifting arm has an efficiency of 35% and required 10 seconds [s] to raise the rock 25 centimeters [cm], how much power in units of watts [W] did the arm use?arrow_forward
- A robot is exploring Charon, the dwarf planet Pluto's largest moon. Gravity on Charon is 0.278 meters per second [m/s2]. During its investigations, the robot picks up a small spherical rock for inspection. The rock has a diameter of 6 centimeters [cm] and is lifted 16 centimeters [cm] above the surface. The specific gravity of the rock is 10.7. The mechanism lifting the rock is powered by a 9-volt [V] power supply and draws 1.09 milliamperes [mA] of current. It requires 13 seconds [s] to perform this lifting task. What is the efficiency of the robot?arrow_forwardA motor has circular cylinders with a 3.875 inch diameter. The height of the cylinder is 4.7 inches and has an ideal gas The piston moves up in the cylinder and compresses the ideal gas. At the end of compression, the cylinder has a volume of 7.37 cubic inches The amount of gas and the temperature of the gas stay the same during compression and the initial pressure in the cylinder is 1.2 atmosphere [atm]. Find the pressure after compression in units of pounds-force per square inch [psi].arrow_forwardA plastic bin with a volume of 1 gallon [gal] has a mass of 0.35 kilograms [kg] when empty and is sitting on a table in a warehouse. After the bin becomes partially filled, 1.3 pounds-force [lb] of force is applied to move the bin across the table, and the bin and its contents accelerate at a rate of 1.5 meters per second squared Ignore frictional losses. Determine the total weight of the bin and its contents in units of newtons [N].arrow_forward
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