A hailstone (frozen water) of diameter 7 cm (at melting point temperature) falls into a lake...
When the air temperature is below 0 C, the water at the surface of a lake freezes to form an ice sheet. The longer the air remains at this temperature, the thicker the ice sheet will become. Will a lake in Minnesota that is uniformly 40 m deep ever freeze solid? To answer this, calculate how long it would take to freeze all the water in the lake. Assume that the upper surface of the ice sheet is steady at...
4. Mixed-Mode Heat Transfer - A transistor capsule is roughly spherical with a 1 cm diameter, covered by a very thin dielectric coating with radiation emissivity E 0.85 The transistor surface is at 60 °C and the surrounding air is at 30°C. The transistor is contained by the black walls of a spherical case with temperature 35 °C, where the case walls are located at a distance H 10 cm from the transistor capsule wall. a) Find the rate of...
An uninsulated metal sphere with a diameter of 1 cm has a surface temperature of 30 °C, and is exposed to flow of water at 0 °C. The water moves in cross flow over the sphere with a velocity of 0.1 m/s. Determine the heat loss from the sphere.
7. When you heat water from just above its freezing point to just below its boiling point, the kinetic energy of the molecules (a) increases by about 18% (b) decreases by about 18% (c) doubles (d) it is impossible to say given this information 8. Anna’s body consists, roughly speaking, of 60 kg of water at human body temperature (37 C). Suppose Anna is standing next to a small frozen pond containing 200 kg of ice at 0 C. Which...
10) When the air temperature is below 0 Celsius, the water of a lake freezes to form an ice sheet. The time required to freeze the ice sheet is proportional to the thickness squared if the heat of fusion of the water freezing on the underside of the sheet is conducted through the sheet. Assuming the upper surface of the sheet is at -10 Celsius and the bottom at 0 Celsius, calculate the time it will take to form an...
Consider a 2-m-high electric hot-water heater that has a diameter of 40 cm and maintains the hot water at 60 C. The tank is located in a small room at 20°C whose walls and ceiling are at about the same temperature. The tank is placed in a 44-cm-diameter sheet metal shell of negligible thickness, and the space between the tank and the shell is filled with foam insulation. The average temperature and emissivity of the outer surface of the shell...
A glass tumbler of 200 g mass and 5 cm inside diameter is filled to a depth of 10 cm with tap water whose temperature is 10 degrees C, and at 50 g of ice 0 degrees C are then added. At the end of an hour, it is noticed that the ice has just finished melting. What was the average rate, in calories per second, at which heat flowed into the glass from its surroundings?
Q4 04(12%) Water is to be heated from 10°C to 80°C as it flows through a 2-cm-internal-diameter, 7-m-long tube. The tube is equipped with an electric resistance heater, which provides uniform heating throughout the surface of the tube. The outer surface of the heater is well insulated, so that in steady op eration all the heat generated in the heater is transferred to the water in the tube. If the system is to provide hot water at a rate of...
Conceptual What happens to the temperature when the water reaches its melting point? 1. 1. Create a heating curve of temperature v. time for water in Exploration 1. Select three different colors to represent changes in temperature over time as the heat energy input changes in each of the three trials. How does varying the heat energy affect the resulting temperature v. time graph? You can attach your graph or just state your observation based on the question asked. Conceptual...
S A 10-m-long section of an 8 cm (r=4 cm) of external diameter horizontal steam water pipe passes through a large room whose temperature is To =15°C. The pipe is insulated with an insulating material of conductivity k=0.01 W/m-°C and 1 cm thick. If the inner surface temperature of the pipe is 95 °C (at r2) and the pipe is exposed to a cross wind of 6.0 m/s, determine the rate of heat loss from the pipe (neglect radiation). Thermal...