4 ms·
But did you know that it was over 1 kW and under 1 GW? (And if no, were you enrolled in a Physics Electricity & Magnetism course at the time.)
by droithomme 7y ago
But did you know that it was over 1 kW and under 1 GW?
(And if no, were you enrolled in a Physics Electricity & Magnetism course at the time.)
- metaphor 7y agoIt's a meaningless question if the person answering it simply doesn't have some qualitative frame of reference to gain intuition from...and gaining intuition on EM phenomena grounded in reality isn't easy; there'd be a lot more EEs and physicists out there otherwise. Besides, if you're walking into a time-constrained exam of toy questions, I fail to see what incentive a student may have to corroborate toy answers against a reality that it may or may not be an approximation of.
- skissane 7y agoA lot of household appliances have power measured in watts (microwave ovens, electric heaters, etc). And megawatts and gigawatts are commonly used in discussion of electric power plants. My electricity bill is in kilowatt-hours, and that's what my electricity meter says on the front as well. Isn't that enough background knowledge to guess that an electric car would likely be more than a kilowatt (my microwave oven is more than that) but less than a gigawatt (a decent sized power station?)
- bsder 7y agoNo, not offhand. If someone, at some point, had said that kiloWatts and Horsepower are the same order of magnitude, I might have been a little better about that. Gigawatt would have set off my "Huh?" detectors as I have heard that in correspondence with power plants. However, given that diesel generators sometimes power buildings, it would not have set off too much worry.
- jsjohnst 7y ago> However, given that diesel generators sometimes power buildings How much power do you think a building typically draws? To give a few examples for scale: - typical U.S. home draws between 1KW to 25KW of electricity. - typical U.S. large shopping mall around 1MW - typical large data center with tens of thousands of servers + cooling is in the 5 to 15MW range As a bonus: a fully loaded 747 weighing 400 tons on takeoff is around 90MW (aka 120,000HP). And to circle back to the diesel generator, while size can very, they are fairly commonly around 1,000 - 1,500hp which translate to around 1MW.
- msla 7y agoOK, how much intuition do you have for dynes? And that's metric, not some odd British system.
- Symbiote 7y agoMetric, but not SI, and obsolete. I own many things labelled in watts: laser pointer, phone charger, light bulbs, speakers, computer, fridge, tumble drier, oven. That covers mW, W and kW. Hundreds of MW to 1 or 2 GW is familiar as the output of a power station. Vehicles are obviously in between.
- hyperbovine 7y agoI don’t know why you’re getting downvoted. 1kW is a microwave, and 1GW is a nuclear power plant. It seems not unreasonable to expect people to understand this.
- bsder 7y agoMaybe, but the fact that a high end commercial microwave is about the same amount of power as my car rolling along at about 30mph(45kph) on a level road would have surprised my intuition initially. I would have pegged a car for MUCH higher power output. So, while I probably wouldn't have pegged a dragster at GW, I might have pegged it at 50-200MW assuming I put my car at an incorrect 200kW on average as opposed to top end (assuming a dragster is at least 100x a bog standard car wouldn't be out of bounds). In addition, assuming that a dragster has an instantaneous (or short lived) power output on the same level as a diesel power plant (designed to be continuous) probably also isn't out of whack. My estimates are still hilariously out of whack--simply because my errors are compounding in the same direction. I have had this happen at other times. RF level strength loss due to antennas is one of those. I was hunting a problem and saw the signal but something like -90dbm down. I mumbled that "Wow, did we get our antenna match that wrong?" An experienced RF engineer looked at me and laughed "If you have an antenna that can actually kill a +20dbm signal to better than -90dbm, you should patent it. Check the firmware. Power amp probably isn't turned on." He, of course, was completely correct because he knew that killing an RF signal more than 50dbm or so gets really hard.