Well since you can only heat your home/water with it and your home stove is less efficient than say the zero-emmisions one in gillete WY. and the distribution cost placed on top of that. you would pay more than the coal-made-electricity. plus you would burn more for the same effect. and coal decomposes in oxygen so that's not EPA condoned anymore. so the answer is. . . none. its more advantageous to just use the electricity
It must be noted that during an elastic collision both the momentum and kinetic energy are conserved. For the kinetic energy, it can be solved through the equation,
KE = 0.5mv²
Equating the kinetic energies before and after collision,
0.5(60)(8 m/s)² = (0.5)(60)(x²) + (0.5)(0.45)(35 m/s)²
The value of x from the equation is approximately 7.40 m/s