About how much pressure do the feet of a 6000 kg elephant exert on the ground assuming each foot has an area of 0.10 square meter

As you know, the Pressure is calculated by: force divided by area. 
Therefore, plugging in our known values:
Force is equal to 6000Kg then covert this to Newtons = 6000 kg x 9.81 N = 58680

Area is 4*(.1m^2) = .4m^2

Pressure: 58680 N / .4 m^2  = 150,000 N/m^2

12000j is work done

their crystal patterns have been disrupted by stress