Physics
posted by Priscilla .
A 2.0kg rock falls from a height of 25 m to a point 20 m above the ground.
How much potential energy does it lose?
GIVEN:
mg = 2.0 kg
h/d = 5 m
PE = mgh
PE = (2)(5)
PE = 10 J

NO. PE=mgh
you did not include the value of g. 
OK, i was told by my teacher that mg would equal together 2 kg. If your including g then:
PE = mgh
PE = (2)(9.8)(5)
PE = 98 J