In which of these situations, is mechanical energy being conserved? (Neglect, air resistance, friction and breaking) Check all that apply.

Child on a swing

Pendulum

Bow and Arrow

Roller Coaster

Neglecting, air resistance, friction and breaking, all the condition has conservation of mechanical energy.

Explanation:

The law of conservation of mechanical energy suggests that the mechanical energy in a locked system with out any destructive forces like friction or air resistance remains always the same (constant). The energy may be converted between kinetic energy, potential energy, gravitational potential but energy do not get decreased in any cases as mentioned in the option. So all the cases mentioned above shows the conservation pattern of mechanical energy.