A 1.5 kg iron is moved from the wrist to the neck of a shirt, and back down to the wrist. The total length of this shirt's sleeve is 0.65 m. The coefficient of kinetic friction between the iron and the shirt is 0.26.Calculate the total work done by friction moving this iron back and forth and determine whether friction is a conservative or non-conservative force.My question:Why is the length of the shirt negative.