Answer
(a) The energy that is saved is $1.176\times 10^7~J$
(b) The energy that is saved is $3.125\times 10^6~J$
Work Step by Step
(a) We can find the gravitational potential energy:
$U_g = mgh = (100~kg)(9.80~m/s^2)(12,000~m) = 1.176\times 10^7~J$
The energy that is saved is $1.176\times 10^7~J$
(b) We can find the kinetic energy:
$KE = \frac{1}{2}mv^2 = \frac{1}{2}(100~kg)(250~m/s)^2 = 3.125\times 10^6~J$
The energy that is saved is $3.125\times 10^6~J$.
