A person is walking outdoors on a cold day when the temperature is -20°C. He is breathing at the rate of 16 breaths per minute, and each time he breathes in he inhales 0.0050 m3 of air
At what rate does he lose heat from breathing if the air in his lungs is heated to body temperature (37°C) before it is exhaled? The specific heat of air is 1020 J/kg ? K and the density of air is 1.29 kg/m3.
A) 90 W B) 150 W C) 60 W D) 100 W E) 300 W
D
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The _____ is a geologically brief period about 540 million years ago during which fossil evidence indicates Earth life became complex and diverse
A) Cambrian explosion B) Paleozoic era C) Renaissance D) Ordovician
A super-insulated house is at a temperature of 20°C. The temperature outside is 0°C. The surface area of the house is 200 m2, and the emissivity is 1 . Approximately how much energy is radiated (in W) per second?
a. 20 000 b. 2 000 c. 200 d. 2 e. 0.2
A swimmer swims 20 laps in a north-south facing pool in 7.00 minutes. Her first lap is toward the north. Her displacement and average velocity are
a. 0; 0. b. 0; 2.38 m/s, south. c. 0; 2.38 m/s, north. d. 1 000 m, south; 2.38 m/s, south. e. 1 000 m, north; 2.38 m/s, north.
A load of steel of mass 6000 kg rests on the flatbed of a truck. It is held in place by metal brackets that can exert a maximum horizontal force of 8000 N
When the truck is traveling 20.0 m/s, what is the minimum stopping distance if the load is not to slide forward into the cab?