A girl of mass m_G is walking up a slippery slope while pulling a sled of unknown mass; the slope makes an angle theta with the horizontal. The coefficient of static friction between the girl's boots and the slope is mu_s; the friction between the sled and the slope is negligible. It turns out that the girl can pull the sled up the slope with acceleration up to a without slipping down the slope. Find the mass of the sled m_S. Assume that the rope connecting the girl and the sled is kept parallel to the slope at all times. Find the mass of the sled m_S. Express the sled's mass in terms of the given quantities and g, the magnitude of the acceleration due to gravity. I would like to think it involves using something like: Code (Text): cos(theta)=x/(Mg-Ms) What other variables and I missing?