Inclined airtrack: Cart and ball accelerate in unison.

Cart and ball accelerate in unison. An air cart with two perpendicular support rods is placed at the top of an inclined airtrack at angle 'theta'. A ball hangs by a string centered between the support rods. The ball and cart are released simultaneously. The accelerations of the cart and ball respectively will depend on 'theta prime', the initial angle of the string with respect to the vertical. (See Fig. 1) In particular, if the string is parallel with the support rods, 'theta prime' = 'theta', and the cart and ball will accelerate as one: the ball remains fixed relative to the cart. Comment : For other values of 'theta prime', the ball will act like a pendulum with an equilibrium position parallel with the support rods. For example, if 'theta prime' < 'theta' , the cart will initially have greater acceleration down the incline and overtake the ball (relative to the support rods).If 'theta prime' > theta, the ball will initially have greater acceleration down the incline and overtake the cart (relative to the support rods).