The height of Niagra falls is 50 m. Calculate the difference in temperature of water at the top and at the bottom of fall, if `J = 4.2 J cal^(-1)`.

Explanation

Here, `h=50 m, g=9.8 ms^(-2), J=4.2 Jcal^(-1)`. Let M be the mass of water that falls and `theta` be the rise in temp. of water at the bottom. As
`J = W/H = (Mgh)/(Ms theta) :. theta=(gh)/(sJ)`
specific heat of water, `s=1000 cal kg^(-1) .^(@)C^(-1)`.
`theta = (9.8 xx 50)/(1000 xx 4.2) = 0.117^(@)C`.