Question

5. Fire hoses used in major structure fires have inside diameters of 2.5 in. The nozzle of the fire hose have an inside diameter of 1.2 in. When firefighters are fighting a fire 2019.007 cm above the ground, the pressure in the nozzle is less than at ground level. When measured, the gauge pressure in the nozzle is 0.00 Pa. (a) (2p) How are the firefighters able to fight a fire with zero water pressure? Explain your answer (b) (2p) What is the value of the water pressure as it emerges into the air from the nozzle? Explain your answer 6. Mickey and Minnie decided to build their own Carnot's perfect heat engine using same temperature difference between-hot and cold reservoirs, Δ 100°C, Mickey used a cold reservoir with the temperature- 10°C. Minnie decided to use a hot reservoir with the temperature 50°C (a) (1p) Calculate the efficiency of Mickey's engine. Show your work. (b) (1p) Calculate the efficiency of Minnie's engine. Show your work. (c) (2p) Which one was able to build a more efficient engine, Mickey or Minnie? 7. (a) (2p) The sounds at the extremes of the audible range have the frequencies 20 Hz and 20 kHz. Calculate the corresponding periods to these frequency values. Show your work. Express your results in the appropriate SI units (b) (2p) You may learn in the future that light is an electromagnetic wave that can travel through a vacum. Can sound waves travel through a vacuum? Explain your answer.

Answer 1

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