All moving objects have momentum. Forces can cause changes in momentum. The total momentum in a collision or explosion is conserved and stays the same. Car safety features absorb energy involved in a crash they slow down the collision thus reducing the force of impact.
A transformer is an piece of electrical apparatus which will increase or decrease the voltage in an alternating current. It can be designed to "step up" or "step down" voltages and is based on the magnetic induction principle.