1. *The primary and secondary mirrors of a space telescope are assembled using zerodur spacers in...

 

 

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1. *The primary and secondary mirrors of a space telescope are assembled using zerodur spacers in an engineering laboratory in which the room temperature is 20 C. In space the telescope will drop to -30 C. If the distance between the mirrors is exactly 80 cm in the lab, how much would the length of the zerodur spacer change in space? The properties of the material Zerodur can be found in the following table. Zerodur Properties of Zerodur Coefficient of Thermal Specific Heat Expansion 2 x 10-8 [K-1] 3347.20 [J/kg/K] 50 50 - 80 cm 2. *Steel rails 20 m long are laid on a cold winter day at 14F. How much space must be left between the rails to allow for expansion at a summer temperature of 104F? 3. *The tires on a race car are filled with air at 10 C, to a gauge pressure of 35 lb/in2 (about 2.4 x 105 Pa). The gauge pressure is the difference between the pressure in the tire and the atmospheric pressure outside the tire. During the race, the tires heat up to 120 C. What will be the gauge reading for the tire pressure at this temperature? 4. *A canister containing 8g of helium gas (atomic mass 4.0 u) was used to fill up party balloons. When the canister was full, the pressure in the gas was 3 atmospheres and its temperature was 27 C. After filling the balloons, the pressure was seen to have dropped to 2 atmospheres and the temperature dropped to 17C. Exactly how many grams of helium gas were used to fill the balloons? 5. *An ideal gas is enclosed in a cylinder with a movable piston on top. The piston has a mass of 8 kg and an area of 5 cm and is free to slide up and down, keeping the pressure of the gas constant. How much work is done by the gas as the temperature of 0.2 mol of the gas is raised from 20 C to 300C? 6.* 7.* A 0.050-m tank holds hydrogen (H2) at a pressure of 4 106 Pa at a temperature of 300 K. How many molecules (that's molecules, not moles) are contained in the tank? Gas in a propellant tank on board a spacecraft registers a pressure of 8,000 Pa when it is at 20 C. When the spacecraft turns so that the tank is in direct sunlight, its temperature rises to 40 C. What is the new pressure in the tank? [Hint: If you got 16,000 Pa you had better think about the question again.] 1. *The primary and secondary mirrors of a space telescope are assembled using zerodur spacers in an engineering laboratory in which the room temperature is 20 C. In space the telescope will drop to -30 C. If the distance between the mirrors is exactly 80 cm in the lab, how much would the length of the zerodur spacer change in space? The properties of the material Zerodur can be found in the following table. Zerodur Properties of Zerodur Coefficient of Thermal Specific Heat Expansion 2 x 10-8 [K-1] 3347.20 [J/kg/K] 50 50 - 80 cm 2. *Steel rails 20 m long are laid on a cold winter day at 14F. How much space must be left between the rails to allow for expansion at a summer temperature of 104F? 3. *The tires on a race car are filled with air at 10 C, to a gauge pressure of 35 lb/in2 (about 2.4 x 105 Pa). The gauge pressure is the difference between the pressure in the tire and the atmospheric pressure outside the tire. During the race, the tires heat up to 120 C. What will be the gauge reading for the tire pressure at this temperature? 4. *A canister containing 8g of helium gas (atomic mass 4.0 u) was used to fill up party balloons. When the canister was full, the pressure in the gas was 3 atmospheres and its temperature was 27 C. After filling the balloons, the pressure was seen to have dropped to 2 atmospheres and the temperature dropped to 17C. Exactly how many grams of helium gas were used to fill the balloons? 5. *An ideal gas is enclosed in a cylinder with a movable piston on top. The piston has a mass of 8 kg and an area of 5 cm and is free to slide up and down, keeping the pressure of the gas constant. How much work is done by the gas as the temperature of 0.2 mol of the gas is raised from 20 C to 300C? 6.* 7.* A 0.050-m tank holds hydrogen (H2) at a pressure of 4 106 Pa at a temperature of 300 K. How many molecules (that's molecules, not moles) are contained in the tank? Gas in a propellant tank on board a spacecraft registers a pressure of 8,000 Pa when it is at 20 C. When the spacecraft turns so that the tank is in direct sunlight, its temperature rises to 40 C. What is the new pressure in the tank? [Hint: If you got 16,000 Pa you had better think about the question again.]