A champion athlete can produce one horsepower (746 W) for a short period of time. If a 70-kg athlete were to bicycle to the summit of a 500-m high mountain while expending power at this rate, she would have used at least ____ J of energy.
1) 746
2) 3.43 ´ 105
3) 3.73 ´ 105
4) 7.46 ´ 105
5) 2.61 ´ 107
Answer: 2