Question

forty 2.0 kg blocks 20.0 cm thick are used to make a retaining wall in a backyard. Each row of the wall will contain 10 blocks. you may assume that the first block is the reference level. How much gravitational potential energy is stored in the wall when the blocks are set in place.

I know the formula for GPE=mgh
I did 40*2 to find total mass being 80 kg.
How would I find the center of mass?

Answer 1

assuming the BOTTOM of the first block is reference level, then in a 4 block height (40/10) the avg height is at 40 cm, two blocks below, and two blocks above. This will be the center of mass level.

GPE=mgh=40*.4m*2kg*g=...