Answer:
Step-by-step explanation:
Given
mass of ball =2.1 kg
height of room =3 m
Length of string=1.1 m
Gravitational Potential Energy of ball relative to the ceiling
=mgh
where h is distance between ceiling and ball

=-22.638 J
negative indicates ball is below the reference Plane
(b)Gravitational Potential Energy of ball relative to the Floor
=mgh
here h=3-1.1=1.9 m

(c)Gravitational Potential Energy of ball relative to a point at the same elevation as the ball
=mgh
here h=0 as it is in the same plane as of ball
=0