What happens to mechanical energy if the potential energy of an object decreases? a. mechanical energy decreases. b. mechanical energy increases. c. mechanical energy increases and then decreases. d. mechanical energy remains unchanged.

D. Mechanical energy remains unchanged.

Mechanical energy = Potential energy + Kinetic energy

So if potential energy decreases, then kinetic energy must increase so that the system is balanced.

if the person is shown to have +90n, then ans is -10n.

if the person is shown to have -90n, then ans is +10n.

causes

fossil fuels burn

cities become more industrialized

human population grows worldwide