The old style (incandescent) light bulb converts more energy into heat than it does into light. If you're using it mainly as a source of light, then it's a bummer, and its efficiency is very low. BUT ... if you're using an incandescent light bulb as a heater, then its efficiency is much better. It all depends on your point of view.
Balanced forces are equal and opposite forces that act on the same object. ... Action-reaction forces are equal and opposite forces that act on different objects, so they don't cancel out. In fact, they often result in motion.
