Question

An elite tour de france cyclist can maintain an output of 420 watts during a sustained climb. at this output power, how long would it take a 78 kg cyclist (including the mass of his bike) to climb the famed 1100 m high alpe d'huez mountain stage? neglect any friction.

Answer 1

2002 seconds, or 33 minutes, 22 seconds. First, let's calculate how many joules it will take to lift 78 kg against gravity for 1100 meters. So: 78 kg * 9.8 m/s^2 * 1100 m = 840840 kg*m^2/s^2 Now a watt is defined as kg*m^2/s^3, so a division of the required joules should give us a convenient value of seconds. So: 840840 kg*m^2/s^2 / 420 kg*m^2/s^3 = 2002 seconds. And 2002 seconds is the same as 33 minutes, 22 seconds.