This whole treating spermatozoa as race cars stunt got me curious about how many horsepower their engines pack. I've found a paper[1] where optical tweezers[2] were used to determine they produce 44 ± 20 pN of force. A figure often quoted for their speed is around 5 mm/min. Force*Velocity has units of Power, so the product of the two gives a power estimate of ≃ 3.7 ± 1.7 femtowatt, or 4.9 ± 2.2 attohorsepower. This estimate is close to figures from simulations in another paper[3], that gave results in the range of 6-9 femtowatt (8-12 attohorsepower):
> In the walled simulation, the power consumption is 0.0127 pW, which is likely to be close to the actual power consumption of the sperm, but it is underestimated by almost fifty per cent, with an average of 0.0084 pW, when walls are ignored. Again, it can be seen that the instantaneous power consumption varies throughout the beat cycle. Cell σ2 has beat frequency component of 11.22 Hz contributing 70 % of the tail amplitude and a component at 15.24 Hz contributing 30 % of the amplitude and so (3.1) gives a power prediction of 0.006–0.009 pW.
The Saturn-V rocket had a power rating of 160,000,000 hp[4]. That probably gives the Apollo astronauts among all humans the more extreme ratio between minimum and maximum power output of travel means across the whole lifecycle, spanning 25 orders of magnitude.
Qem•9mo ago
> In the walled simulation, the power consumption is 0.0127 pW, which is likely to be close to the actual power consumption of the sperm, but it is underestimated by almost fifty per cent, with an average of 0.0084 pW, when walls are ignored. Again, it can be seen that the instantaneous power consumption varies throughout the beat cycle. Cell σ2 has beat frequency component of 11.22 Hz contributing 70 % of the tail amplitude and a component at 15.24 Hz contributing 30 % of the amplitude and so (3.1) gives a power prediction of 0.006–0.009 pW.
The Saturn-V rocket had a power rating of 160,000,000 hp[4]. That probably gives the Apollo astronauts among all humans the more extreme ratio between minimum and maximum power output of travel means across the whole lifecycle, spanning 25 orders of magnitude.
[1] https://www.researchgate.net/profile/Karsten-Koenig-3/public...
[2] https://en.wikipedia.org/wiki/Optical_tweezers
[3] https://eprints.gla.ac.uk/6249/1/6249.pdf
[4] https://www.skyatnightmagazine.com/space-missions/saturn-v-r...