• Your bike, you start and accelerate to a speed of 5 m/s in 30 s over a distance of 75 m, and keep going at this speed on a level ground for a further 1 km. During your trip, the average drag force on you is 15 N, and the average rolling friction force is 10 N. Assume 80 kg total mass of yourself and the bike, 25% mechanical energy efficiency in your body, and a BMR of 100 W. 
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• (a) Calculate the work done by the rolling friction and air drag, and the change in your mechanical energy (in Joules).
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• (b) Calculate the total mechanical power output (P_out) averaged over the entire trip (in Watts).
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• (c) Calculate the total average metabolic power (P_in) that you need to accomplish this (in Watts)