Question

At one instant, a falling object has 40 J of potential energy, and 20 J of kinetic energy. Later, it has only 25.5 J of potential energy. If mechanical energy has remained constant, how much kinetic energy does it have? ⠀⠀​

Answer 1

34.5 J

Step-by-step explanation:

ME = PE + KE

Total Mechanical Energy is always conserved, so ME remains same as the object falls. As PE decreases, KE increases.

Instant 1: ME = 40 J + 20 J = 60 J

Instant 2: ME = 60 J = 25.5 J + KE

KE = 60 J - 25.5 J = 34.5 J