A block slides down a frictionless incline kept on the floor of a chamber . Find the acceleration of the block relative to the incline when the chamber is carried by a helicopter with upward acceleration a at inclination `theta` with the vertical . Consider the special cases when `theta = 0 ^(@)` and `theta = 90^(@)` . The inclination of the plane is `90^(@) - alpha` to the vertical in the same sense as `theta` .
