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प्रश्न
How is the power related to the speed at which a body can be lifted? How many kilograms will a man working at the power of 100 W, be able to lift at a constant speed of 1 m s–1 vertically? (g = 10 m s–2)
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उत्तर
Power associated in lifting a body of mass m upto a height h in time t is,
p = `("mgh")/"t"`
Here, `"h"/"t"` = speed = v
∴ P = mgv
Here P = 100W, v = 1ms−1,10 ms−2
m = `"P"/"gv"`
So, m = `(100 "W")/(10 "ms"^-2 xx 1 "ms" ^-1)`
= 10 kg
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