Given a, h=210m Specific heat of water, c=4.2×103Jkg−1K−1 When water falls on the surface of earth, then its potential energy is converted into kinetic energy. ∴ Kinetic energy = Potential energy KE=mgh......(i) According to question, Heat produced =60% of KE [from Eq. (i)] ⇒‌‌mc∆T=‌