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Consider a drop of rain water having mas...

Consider a drop of rain water having mass `1 gram` , 50 `m//s` Take `g` constant with a volume `10 m//s^(2)`. The work done by the
(i) gravitational force and the
(ii) resistive force of air is :

A

(i)-10J,(ii)-8.25J

B

(i)1.25J,(ii)-8.25J

C

(i)100J (ii) 8.75J

D

(i)10 J (ii)-8.75 J

Text Solution

Verified by Experts

The correct Answer is:
d
(d)Thinking process By work -KE theorem, we have change in KE= work done by all of the forces,
`W_(g)=mgh=10^(-3)xx10xx1xx10^(3)=10J`
Now, from work-KE theorem, we have
`DeltaK=W_("gravity")+W_("air resistance")`
`implies1/(2)xxmv^(2)=mgh+W_("air resistance")`
`W_("air resistance")=(1)/(2)mv^(2)-mgh`
`=10^(-3)((1)/(2)xx50xx50-10xx10^(3))`
` =8.5J`
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  • Consider a drop of rain water having mass 1 g falling from a height of 1 km. It hits the ground with a speed of 50 m/s. Take 'g constant with a value 10 m/ s^2 . The work done by the (1) gravitational force and the (ii) resistive force of air

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    (i) 1.25 J (ii) -8.25 J
    B
    (i) 100 J (ii) 8.75 J
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