Alternative power/recharging source?

[Carl-Daniel Hailfinger]

On 22.02.2008 23:41, Ben Goetter wrote:
>  >> hours...using gravity! :-) (Consider the XO using
>  >> about 2 watts...)
>
> There seems little danger of this mechanism being useful on Earth for 
> the XO-1.  A 30kg human child who can move her own mass a meter 
> vertically (via a series of pulleys, or perhaps just climbing stairs 
> with a buddy riding piggyback etc.)

If the child has a mass of 30 kg, why should he/she carry anything else 
piggyback one meter upwards to gain 300 J of potential gravitational 
energy (assuming g=10 m/s^2)? The child already gets that potential 
enery if it climbs the stairs alone.

> can invoke only 300J of potential 
> gravitational energy, or enough to let an XO sleep for two and a half 
> minutes assuming a 100% efficient conversion from gravitational to 
> electrical potential.
>   

Regards,
Carl-Daniel

-- 
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