% ============================================================================
% UpdateMass.m
% Author: Brent Dingle, Ph.D.
% Creation Date: 2020
%
% rock.thrust must be set correctly prior to calling this functon
% ============================================================================
function mass = UpdateMass(sim, rock)
  burnRate = rock.fuelRatePerN * rock.thrust;   % (kg/s) = (kg/s)/N * N
  massBurned = burnRate * sim.dt;               % kg = kg/s * s
  
  % TODO: could flag an error if massBurned > rock.fuelMass
  % Assumed: because dt is small this error should be equally small
  newMass = rock.fuelMass - massBurned;
  if (newMass < 0.0)
    newMass = 0;
  endif
  
  mass = newMass;

endfunction