Engineering, 07.04.2020 17:00, SignoraPenguino
A standard D cell can supply 10mA at 1.5 volts for about 300 hours. An alkaline D cell can do about the same. Assume - 2 - that the chemistry of the batteries will produce the same amount of energy and will maintain the same EMF regardless of the current drawn from the battery. However, the internal resistance of a standard D cell is about 1 ohm and the internal resistance of an alkaline cell is about 0.1 ohm, so the amount of energy dissipated internally is different. Let us suppose that you have a multi-speed winch that is 50% efficient and that your mass is 60kg.
(a) If the winch is set to super-slow speed how high can one of these batteries lift you before it is exhausted?
(b) What is the fastest rate (in cm/sec) that each battery can lift you?
(c) At this fastest lift rate, what is the maximum height that you achieve before the battery dies? How long does it take?
Answers: 2
Engineering, 04.07.2019 18:10, kevin72836
Consider a large isothermal enclosure that is maintained at a uniform temperature of 2000 k. calculate the emissive power of the radiation that emerges from a small aperture on the enclosure surface. what is the wavelength ? , below which 10% of the emission is concentrated? what is the wavelength ? 2 above which 10% of the emission is concentrated? determine the wavelength at which maximum spectral emissive power occurs. what is the irradiation incident on a small object placed inside the enclosure?
Answers: 2
Engineering, 04.07.2019 19:20, littlepotato10
To save energy, the air supply to a 2000 ft office has been shut off overnight and the room temperature has dropped to 40°f. in the morning, the thermostat is reset to 70°f and warm air at 120 f begins to flov in at 200ft'/min. the air is well mixed within the room, and an equal mass flow of air at room temperature (changing with time) is withdrawn through a return duct. the air pressure is nearly 1 atm everywhere. ignoring heat transfer with the surroundings and kinetic and potential energy effects, estimate how long it takes for the room temperature to reach 70°f. plot the room temperature as a function of time.
Answers: 1
Engineering, 05.07.2019 19:10, justin20080
Tech a says never use a water hose to clean up dust after a repair. tech b says never use a floor scrubber to clean up dust after repairs. who is correct?
Answers: 1
A standard D cell can supply 10mA at 1.5 volts for about 300 hours. An alkaline D cell can do about...
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