The athlete Emily Davis won the 100 m sprint gold medal at London Olympic 2012 setting a new Olympic record of 10.54 s . Assume that she achieved her maximum speed in a very short time and subsequently ran the race with that speed till she crossed the line. Take her mass to be 50 kg . Assuming that the track, the wind etc. offered an average resistance of one tenth of her weight, calculate the work done by the resist

Step-by-step solution

Mass of the athlete, m = 50 kg Acceleration due to gravity, g = 9.8 m/s ^2 Weight of the athlete, W = mg = 50 9.8 = 490 N Average resistance force, f = 1 10 W = 1 10 490 = 49 N Displacement of the athlete, s = 100 m Since the resistance force acts in the direction opposite to the displacement, the angle between them is 180^ . Work done by the resistance, W_R = f s (180^ ) = -f s W_R = -49 100 = -4900 J