The mechanical energy consisting of potential and kinetic energy is:
0.001 x [ (acceleration of gravity x height) + (1/2) (speed)² ] .
You want to know how much [ mc² ] there is in 1 gram of mass.
E = m c² = (0.001) x (3 x 10⁸)² = 9 x 10¹³ joules
That's the energy that a 1,000-watt toaster uses
in 2,852 years of continuous toasting.~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~Hope that helped!