State which of the following situations are possible and give an example of each of the following: (a) an object with a constant acceleration but with zero velocity, (b) an object moving in a certain direction with an acceleration in the perpendicular direction.

(a) Yes, a body can have acceleration even when its velocity is zero. When a body is thrown up, at highest point its velocity is zero but it has acceleration equal to acceleration due to gravity.

(b) Yes, an acceleration moving horizontally is acted upon by acceleration due to gravity that acts vertically downwards.