How many foot pounds of work does it take to throw a baseball 90 mph? A baseball weighs 5 oz, or 0.3125 lb. The only equation I can find is W= (change) KE, where KE=1/2mv^2 When I try plugging in the data given I'm not getting the correct answer. I don't know if I'm doing incorrect unit conversions or what. This is actually in my calculus book physics but this seemed like the more appropriate place to post the question. By the way, the answer in the book is 85.1 ft-lbs. Please help me. I'm dyin' over here.