Inertia

Inertia is a resistance to change in energy. The more massive something is, the harder we have to push to change its speed or direction. There’s a time delay in the energy transfer.

This is because energy transfers are about readjusting sizes of particles. For an object to change its speed or direction, all its particles have to change. For large objects, this requires a lot of time.

Inertia is the time delay registered when energies of particles are changed or readjusted.