A large rock rests on a ledge 31.2 m above a lake.  If the rock has 2.65 x 10⁵ J of gravitational potential energy relative to the surface of the lake, what is the mass of the rock?  

You MUST

 show

all work starting with the formula (and rearrangement if needed).  The formula must use symbols for formulas introduced

in the VVS course.  Next, you need to

show the substitution of values into the formula, then the calculated

answer.  Remember to include units and use correct significant digits in

your final answer.  Responses only showing the final answer will receive a

zero grade.