The amount of kinetic energy depends on the mass and the speed. The kinetic energy of an object is directly proportional to its mass and speed. So, if the mass of a body increases, it’s kinetic energy also increases even if the velocity remains constant. So, yes, Robert’s kinetic energy will be twice as much. Also, think of it this way-since Robert has twice the mass as his sister, he will also need twice the amount of kinetic energy to run in the same velocity as his sister.