Hailstones fall from a certain height. If they melt completely on reaching the ground, find the height from which they fall. (`g=10ms^(-2),L=80` calorie/g and J=4.2 J/calorie.)

Explanation

On reaching the ground, a hailstone of mass M losses potential energy which is converted into he energy required to melt it. In Sl, potential energy required for melting the hailstons
`Mgh=MLrArrgh=L`
`h=(L)/(g), h=(80xx4.2xx1000)/(10)`
`=33.6xx1000m=33.6km`.