Question

a 400-g ball is released from rest at a hieght of 10m. ignoring air resistance, determine the GPE, KE, and total mechanical energy at each of the following heights: 10m, 7.5m, 5m and 2.5m

Answer 1

$\text{GPE: }E_p(h)=mgh.\\ \text{KE: }E_k(h)=mg(h_\text{max}-h).\\ \text{Total: }E_t(h)=\text{const}=mgh_\text{max}.\\\space\\ 10\text{ m}:\\ E_p=39.2\text{ J}.\\ E_k=0,\\ E_t=39.2\text{ J}.\\\space\\ 7.5\text{ m}:\\ E_p=29.4\text{ J}.\\ E_k=9.8\text{ J},\\ E_t=39.2\text{ J}.\\\space\\ 5\text{ m}:\\ E_p=19.6\text{ J}.\\ E_k=19.6\text{ J},\\ E_t=39.2\text{ J}.\\\space\\ 2.5\text{ m}:\\ E_p=9.8\text{ J}.\\ E_k=29.4\text{ J},\\ E_t=39.2\text{ J}.\\\space\\$