A cyclist coasts down a 7.2 degree hill at a steady speed of 10 km/h. If the total mass of the bike and rider is 75 kg, what power output must the rider have to climb the hill at the same speed?
Power = Energy/Time
Ek = 1/2mv^2 where m is the mass v is the velocity and Ek is the kinetic energy
Eg = mgh where m is the mass g is a constant value of 9.8 h is the height above the ground and Eg is the gravitational potential energy.
The Attempt at a Solution
Power = Energy/Time = (Ek + Eg)/Time = [1/2(75)(2.777)^2 + (75)(9.8)(2.7sin7.2)]/1 = 522 Watts
Apparently the answer is 511 Watts. Can someone please tell me where i went wrong?