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Raindrops of raidus 1mm and mass 4 mg a...

Raindrops of raidus 1mm and mass 4 mg are falling with a speed of 30 m/s on the head of a bald person. The drops splash on the head and come to rest. Assuming equivaletly that the drops cover a distance equal to their radii on the head, estimate the force exerted by the each drop on the head.

Text Solution

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Given, `r=1 mm=10^-3 m,
`m=4 mg = 4xx 10^-6 kg`
`S= 10^-3 m,`
`V=0, u=30 m/s`
We knw, `a= (v^2-u^2)/(2xx10^-3)= (-30xx30)/(2xx10^-3)
` =-4.5xx10^5 ms^-2` (decelerating)
Taking magnitude only, ltBrgt deceleration = `4.5xx10 m/s^2`
`:. force, F=4xx10^-6xx4.5xx10^5`
`=1.8N`.
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