1. The problem statement, all variables and given/known data The crate has a mass of 80 kg and is being towed by a chain which is always directed at 20º from the horizontal has shown. Determine the crate's acceleration in t = 2 s if the coefficient of static friction is μs = 0.4, the coefficient of kinetic friction is μk = 0.3, and the towing force is P = (90t2) N, where t is in seconds. 2. Relevant equations ΣF = ma 3. The attempt at a solution ΣFx = max Pcos(20º) - μkmg = ma 84.57t2 - 235.44 = (80 kg)a solving for a when t = 2 a = 1.29 m/s2 The answer at the back of my book is a = 1.75 m/s2. I think I'm supposed to consider that static friction force is greater than kinetic friction force, but I can't figure out how to do that.