The height of a waterfall is 84 metre . Assuming that the entire kinetic energy of falling water is converted into heat, the rise in temperature of the water will be (`g=9.8 m//s^(2),J=4.2` joule / cal)

Options

A. `0.2^(@)C`
B. `1.960^(@)C`
C. `0.96^(@)C`
D. `0.0196^(@)C`

Answer

D

Explanation

We use `k=(m(10)(84))/(4.2)=(200m)cal`
`implies k=mcDeltaT`
`implies 200m=mxx10^(3)xxDeltaT`
`implies DeltaT=(200)/(10^(3)=0.2^(@)C`