An objects motion changes study island

As you lift an 88 n box straight upward you produce a power of 72 w. what is the speed of the box?

A55-kg pilot flies a jet trainer in a half vertical loop of 1200-m radius so that the speed of the trainer decreases at a constant rate. knowing that the plane has a speed of 550 km/h at point a, and the pilot experiences weightlessness at point c (i.e., the normal force from the seat bottom is zero), determine (a) the deceleration of the plane, (b) the force exerted on her by the seat of the trainer when the trainer is at point b.

Mechanical energy is when there are no forces causing an object to lose energy. a. increased b. conserved c. decreased d. doubled i need this answer ! .