Answer:
[tex]Ebp=9J[/tex]
Explanation:
Potential energy:
[tex]Ep=mgh[/tex]
m - mass
h - altitude = 20cm = 0.2 m
[tex]Epa=12=0.2(mg)[/tex]
Thus:
[tex]mg=\frac{12}{0.2}[/tex]
[tex]mg=60n[/tex]
In Point B:
[tex]Epb=mg(0.15)[/tex]
[tex]Epb=60(0.15)[/tex]
[tex]Epb=9J[/tex]