From
http://energy.gov/energysaver/electric-resistance-heating
"Electric resistance heating is 100% energy efficient in the sense that all the incoming electric energy is converted to heat. However, most electricity is produced from coal, gas, or oil generators that convert only about 30% of the fuel's energy into electricity. Because of electricity generation and transmission losses, electric heat is often more expensive than heat produced in homes or businesses that use combustion appliances, such as natural gas, propane, and oil furnaces."
Newton's second law says essentially force = mass x acceleration. Do you mean the second law of thermodynamics? It is possible to convert 100% of other forms of energy, mechanical, electrical. etc. into heat energy but not the reverse. The second law of thermodynamics essentially states that for any closed system involving a transfer of energy the entropy or amount of disorder is increasing.