Our physics expert picks his top-five equations, plus a scheme to supply US power needs with a bucket of baseballs. Thanks, ...

The more mass an object has, the more energy in the kinetic energy store. A runner with a mass of 60kg is running at a speed of 1 m/s. Calculate the amount of energy in their kinetic energy store.

That energy is, of course, related to mass in Einstein's famous equation: E=mc 2. So an object's mass is linked to its energy, which bends spacetime – and this curvature of spacetime is what ...