Answer
(a) -38.416 Joules.
(b) Â 43.904 Joules
(c) 0.00 Joules
Explanation
Gravitational potential energy (P.E) is the energy possessed by a body that is at a potential height from the ground.
IT is calculated by the formula;
P.E = mgh
Where m ⇒ mass
      g ⇒ acceleration due to gravity
      h ⇒ height from the ground.
(a) m = 2.8 kg, h = 1.40 m and  g = 9.8 m/s²
Relative to ceiling, the ball is lower, hence the grativational potential energy is lower (negative)
P.E = 2.80 × -1.40 × 9.8
   = -38.416 Joules.
(b) m = 2.80 Kg, h = 3-1.4=1.6 m and g = 9.8 m/s²
P.E = 2.80 × 1.6 × 9.8
    = 43.904 Joules
(c) m= 2.80 Kg, h = 0 m and g = 9.8 m/s²
P.E = 2.80 × 0 × 9.8
    = 0 Joules
There is no relative distance between the two points. So, the energy is zero.
