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Iguazu Falls on the border between Brazil and Argentina is 82 m high. What is the kinetic energy of a kilogram of water just before it hits the bottom of the falls. Assume the water is moving very slowly at the top of the falls.

User Panos Boc
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1 Answer

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Answer:

K = 803.6 J

Step-by-step explanation:

  • Assuming that the water is moving very slowly at the top of the falls, we can treat to the mass of water as dropping from the top.
  • So, all the energy at that point is just gravitational potential energy.
  • Assuming no friction during the fall, total mechanical energy must be conserved, as follows:
  • ΔK + ΔU = 0 (1)

  • \Delta K = K_(f) - K_(i) = (1)/(2)*m*v_(f) ^(2)

  • \Delta U = U_(f) - U_(i)
  • Taking the bottom of the falls as our zero reference level for the gravitational potential energy, we get, Uf =0.
  • From (1), we get:
  • ΔK = -ΔU
  • ⇒ ΔK = - (0 -m*g*h) = m*g*h
  • ⇒ ΔK = 1 kg*9.8 m/s2*82 m = 803.6 J
  • Kf = 803.6 J
User Himal
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