Water drops from a height of 50 m in a waterfall. Find out the rise in temperature of water, if 75% of its energy is converted into heat and absorbed by water.
`(J = 4.2 xx 10^(7) erg cdot cal^(-1) , g = 9.8 m cdot s^(-2))`

Explanation

Here, `W = mgh xx 75/100 and H = mst`
Now, `W = JH or, mgh xx 75/100 = J mst or, t = (mgh xx 75/100)/(Jms)`
`[s = 1 cal cdot g^(-1) cdot^(@)C^(-1)` for water, `g = 9.8 m cdot s^(-2)`
`= 980 cm cdot s^(-2) , h = 50 m = 50 xx 100 cm]`
`= (gh)/(Js) xx 75/100 = (980 xx 50 xx 100)/(4.2 xx 10^(7) xx 1) xx 75/100 = 0.0875^(@)C`.