A ball of mass 8kg falls from rest from a height of100m neglecting air resistance calculate.its total enegy after falling a distance of 400.
F = m*g = 8kg * 9.8N/kg = 78.4 N.
Epmax = F*h = 78.4 * 100 = 7840 Joules.
Ek + Ep = 7840
Ek + 78.4*(100-40) = 7840
Ek + 4704 = 7840
Ek = 7840-4704 = 3136 Joules.
While Ek goes from 0 to 3136 Joules, the
total energy(Ek+Ep) remains constant at
7840 Joules.