Hey, While searching for a solution to a particular problem, I stumbled upon this forum; any help would be greatly appreciated. We're currently working on energy and power, and in spite of my past success with such problems, I couldn't solve this one: A volleyball is dropped from a height of 10m, but hits the ground with a velocity of only 10m/s. Calculate the quantity of work done by air resistance on the ball. Now, as it turns out, our teacher told us that the problem could be solved without the mass, however, he also said that it could prove to be complicated, therefore, he gave us the mass of the ball (500 g). He also gave us the answer, which is 24J. Solving it with the mass is obviously simple: I determined the potential energy and the kinetic energy; if there was a difference between both of them (technically both should be the same due to the fact that the given speed is just before it hits the ground), it was related to the air resistance. Ep = .5kg x 9.8N x 10 Ep = 49J Ek = (.5kg x 10^2)/2 Ek = 25J 49-25 = 24J However, our teacher challenged us to come up with the same answer without using the mass; as it is, I've only managed to partly complete it, though I'm not sure that I'm on the right track. If anyone could help me determine this problem without using the mass, it would be greatly appreciated! I might have gone too far with my explanations, but keep in mind I'm new here. Thanks a lot!