Hey all, 1. The problem statement, all variables and given/known data "Suppose that we could use the energy released when 4 g of antimatter annihilates 4 g of matter to lift a mass 1 km from the Earth’s surface. How much mass could we lift? Answer in units of kg." 2. Relevant equations e=mc^2 w=fd f=ma 3. The attempt at a solution I was attempting to find the energy with e=mc^2 and using .004kg as the mass. Then I tried using work(energy)=force*distance and force=mass*acceleration (using gravitational potential energy) but my answer was incorrect. For the record, i answered 3.67e10 kg but no luck. I'm stumped. :( EDIT: I think the proper way is using the potential energy equation [energy=mass*gravity*height] after I have found energy from [e=mass*speed of light^2] Is this right? Would the total energy released be from .004kg or from .008kg of matter?