Description of the set-up as given in the uploaded file: Consider a rod of length r, viewed from above, one end of which is called m2 and the other end is called m1. m2 is pivoted in a linear bearing so it can freely slide in a straight line in both directions as well as being free to rotate either clockwise or anticlockwise about m2 as the centre of rotation. The linear bearing lies along the x axis. At m1 there is a point mass of m1 kilograms. The rod is given an initial momentary torque to cause it to rotate clockwise about m2.
Assumptions: Other than the force which produced the initial torque there is no subsequent force or torque given to the system from outside. The whole assembly operates in a horizontal plane so is unaffected by gravity. There is no friction. Everything has zero mass except for m1. The linear bearing is long enough to accommodate any range of motion which m2 may undergo.
My analysis: Due to m1's rotation m2 should exhibit simple harmonic motion symmetrically about a point on the x-axis, let this be the point (0,0) in the Cartesian plane. According to Newton's first law of motion the rod should continue to rotate at it's initial angular speed of w1 (omega-1) since (as far as I can tell) there is no torque opposing its rotation. Let theta be the angle the rod makes with the y-axis so that when the rod is in line with the positive x-axis theta = pi/2 radians.
m2's motion: It seems to me that the position of m2 is given by x=rcos(theta). Therefore m2's speed, v2, is the rate of change of x with time, which is -rw1sin(theta). Therefore the magnitude of m2's acceleration, a2, is the rate of change of v2, which is -r(w1)^2cos(theta) (i.e. minus r omega1 squared cos theta). Therefore the magnitude of the force, F2, acting on m2 is m1a2. Therefore the power, P2, in m2's motion is F2v2. The kinetic energy in m2's motion, E2, can be calculated from the kinetic energy formula of 1/2 mv^2 which gives the same result as getting the integral of P2.
Discussion & request for help: If the analysis given above were correct that would mean energy is not conserved in this system since there is a quantifiable power output even if it is constantly changing in direction and magnitude, even though power is not being input to the system. Assuming therefore that the physics used here is flawed, then why and how exactly is it flawed since it is apparently the standard Newtonian mechanics that I know? Also exactly what is the correct physics for this mechanism? The answer to that must among other things be able to show exactly how torque arises which opposes the rod's rotation since it seems clear that as long as the rod rotates then it will provide power to m2's motion. Thanks in anticipation.