Can anyone help me out with this? Here's the question 1. The problem statement, all variables and given/known data A 2.2 kg block sits on top of an even bigger 3.2 kg block. The coefficient of kinetic friction between the two blocks is 0.25. The coefficient of static friction between the 3.2kg block and the floor is 0.32 Find the maximum force that can be applied to the bottom block so the top block doesn't move at all. Apparently this is the answer, but it doesn't make sense to me. (2.2kg+3.2kg)*9.8m/s^2 * 0.32 + 2.2kg * 9.8m/s^2 * 0.25 = 22 N How would I go about doing this? My answer was around 32 N, but apparently its wrong and the above was right. However, it doesn't make sense. Is it correct? [hr] Here's how I think it should be done. 6 kg * 9.8m/s^2 * 0.32 = 18.2 N. This is how much force the friction of the bottom block resists. The top blocks friction is 2.2kg * 9.8m/s^2*0.25 = 5.39 N. So this means that when the bottom block accelerates forward at 2.45 m/s^2 if there were no friction forces the top block would be accelerating at 2.45 m/s^2 relative to the bottom block (backwards). Meaning that the correct answer should be... 2.45 m/s^2 * 6 kg + 18.2 N which is 33 N. But, apparently this is wrong. So, am I right or is the other guy right?