QUESTION 7 Name four (4) factors that affect the amount of radiation received by a surface A from another surface (or source) B? For the toolbar, press ALT+F10 (PC) or ALT+FN+F10 (Mac). T TT Arial AEC 3 (12pt)

(a) Where can lightning take place? (Where can it begin and end?) (b) Describe what is meant by heat lightning and a bolt from the blue.

(a) A shirtless rider under a circus tent feels the heat radiating from the sunlit portion of the tent. Calculate the temperature of the tent canvas based on the following information: The shirtless rider’s skin temperature is 34.0C and has an emissivity of 0.970. The exposed area of skin is 0.400m2. He receives radiation at the rate of 20.0 W—half what you would calculate if the entire region behind him was hot. The rest of the surroundings are at 34.0C. (b) Discuss how this situation would change if the sun lit side of the tent was nearly pure white and if the rider was covered by a white tunic.

(a) A firewalker runs across a bed of hot coals without sustaining burns. Calculate the heat transferred by conduction into the sole of one foot of a firewalker given that the bottom of the foot is a 3.00-mm-thick callus with a conductivity at the low end of the range for wood and its density is 300kg/m3. The area of contact is 25.0cm2, the temperature of the coals is 700C, and the time in contact is 1.00 s. (b) What temperature increase is produced in the 25.0cm3 of tissue affected? (c) What effect do you think this will have on the tissue, keeping in mind that a callus is made of dead cells?

When the metal ring and metal sphere in Figure CQ10.14 are both at room temperature, the sphere can barely be passed through the ring, (a) After the sphere is warmed in a flame, it cannot be passed through the ring. Explain, (b) What if the ring is warmed and the sphere is left at room temperature? Does the sphere pass through the ring? Figure CQ10.14

The Sun radiates like a perfect black body with an emissivity of exactly 1. (a) Calculate the surface temperature of the Sun, given that it is a sphere with a 7.00108m radius that radiates 3.801026W into 3-K space. (b) How much power does the Sun radiate per square meter of its surface? (c) How much power in watts per square meter is that value at the distance of Earth, 1.501011m away? (This number is called the solar constant.)

When watching a daytime circus in a large, darkcolored tent, you sense significant heat transfer from the tent. Explain why this occurs.

Why are thermometers that are used in weather stations shielded from the sunshine? What does a thermometer measure if it is shielded from the sunshine and also if it is not?

Thermography is a technique for measuring radiant heat and detecting variations in surface temperatures that may be medically, environmentally, or militarily meaningful.(a) What is the percent increase in the rate of heat transfer by radiation from a given area at a temperature of 34.0C compared with that at 33.0C, such as on a person’s skin? (b) What is the percent increase in the rate of heat transfer by radiation from a given area at a temperature of 34.0C compared with that at 20.0C, such as for warm and cool automobile hoods? Figure 14.35 Artist’s rendition of a thermograph of a patient’s upper body, showing the distribution of heat represented by different colors.

Integrated Concepts (a) At what depth in fresh water is critical pressure of water reached, given that the surface is at sea level? (b) At what temperature will this water boil? (c) Is a significantly higher temperature needed to boil water at a greater depth?