Answers
n1.) At position #3, total energy will be all in KE because there is no height and no friction
nSo…use ET=KE=1/2mv2
nKE=1/2 x 0.5kg x (25m/s)2
nSo…KE=156.25J=PE (at position#1)
nSo…ΔPE=156.25J=mgΔh
nAnd Δh=31.86m