A rock weighing 98 newtons is pushed off the edge of a bride 50 meters above the ground what was the kinetic energy of the rock before it began to fall?

Answer 1

zero

Answer 2

The potential energy of the rock at the edge of the bridge is given by (PE = mgh), where (m = 98) N and (h = 50) m. Thus, (PE = 98 \times 9.8 \times 50 = 48020) J. None of this energy has been lost, so the kinetic energy before it fell is also 48020 J since the sum of potential and kinetic energy is conserved in the absence of work done by external forces.