A raindrop of mass `1g` falling from a height of `1km` hits is the ground with a speed of `50 ms^(-1)` If the resistance force is proportion to the speed of the drop, then the work done by the resistance force is`("Taking " g: 10ms^(-2))`.

Options

A. ` -8.25 J`
B. ` 8.75 J`
C. ` -8.75 J`
D. ` 8.25 J`

Explanation

Work done by the gravity `(W_(g)= mgh`
` =10^(-3) xx 10 xx 10^(3) = 10J`
By work -energy therom `= W_(g) + W_(res) = Delta KE`
`10 + W_(res) = (1)/(2) xx 10^(-3) xx (50)^(2)`
`W_(res) = - 8.75 J`
Hence, `- 8.75 J` work done due to air resistance and work done due to gravity is equal to `10J`.