4A. PE = MxGxH. (You can consider g as 9.8 / 10m/s as well)
509 J = 12x10xH
509 J = 120xH
H = 509/120
H = 4.24 m
Hope u got the answer....pls rate the answer if it is helpful for u....and I'm sorry I could not understand B part so I didn't do it.
Thank you