Answer
The correct answer is (a) Biking takes $\frac{1}{3}$ of the energy of walking the same distance.
Work Step by Step
We can find the energy used when biking 1 km.
$E = P~t = (300~W)(\frac{1000~m}{4.2~m/s})$
$E = 71,400~J$
We can find the energy used when walking 1 km.
$E = P~t = (300~W)(\frac{1000~m}{1.4~m/s})$
$E = 214,000~J$
The correct answer is (a) Biking takes $\frac{1}{3}$ of the energy of walking the same distance.
