1. The problem statement, all variables and given/known data Edit: Added another picture: ( click The give variables are: Mass of bowling ball = 2 kg Thèta (angle) = 30 degrees The questions: 1. Draw the forces 2. Normal force of bowling ball on 1 plate 3. Force on springs 3. The attempt at a solution The answer to the first question can be seen on the picture. I only drew the forces on one of the plate, since the forces on the other plate are symmetrical. I hope its not too messy, but these are the forces: Fs= force exerted by the spring on the plate, with Fs _|_ the right angle component on the plate. Fn1= normal force exerted by the plate on bowling ball, and Fn'1= force exerted by bowling ball on the plate. (same for Fn2 and Fn'2). Mg = weight of the bowling ball Fo = force exerted by the "joint" on the plate. Are the forces drawn correctly? 2nd question: normal force Fn _|_ is the component of Fn in the vertical direction As there are 3 forces in the vertical direction, I calculated Mg, the one pointing downward. Then I stated that the vertical components of the normal forces are the same, and 2 times on of those should be equal to Mg. Mg = 2 kg * 9,81 m/s² = 19,62 N cos 30 = (Fn _|_) / Fn <=> Fn _|_ = Fn * cos 30 2 Fn _|_ = 19,62 N so Fn_|_ = 9,81 N so Fn = 11,33 N Is this correct? Third question I took l to be the length of one plate. You also now that: (sin 30)/X = sin(60)/R where X = the distance from O to the Fn So X = 0,58 R Then choosing O as center: - Fs _|_ * l + Fn * 0,58 R <=> Fs _|_ = ( Fn * 0,58 R ) / l Fs _|_ => cos 30 = Fs _|_ / Fs So Fs = Fs _|_ / cos 30 Is this correct? Is it possible to know the exact force on the spring? I would say it is impossible because you haven't got enough variables?