1. The problem statement, all variables and given/known data An object is hanging by a [mass-less] string on a [mass-less] pulley from a cart on a desk with a mass of 1.8 kg. The cart has an acceleration of 2.5 m/s^2. Calculate the mass of the hanging object given that: a) There is no friction. b) There is a frictional force of 0.4 N on the wheels of the cart. 2. Relevant equations Fnet = ma 3. The attempt at a solution m1 = 1.8 kg a = 2.5 m/s^2 m2 = ? I don't know where to start with this question... Maybe Fnet = (1.8 kg)(2.5 m/s^2) = 4.5 N ? But what would I do with this. ... I don't know.