Hi, Can anybody offer any assistance with the following problems please: 1. A train is moving along a straight line at constant speed V. Inside a carriage an object is thrown upwards from a height h (measured from the floor of the carriage) with initial velocity v. Determine the trajectory of the object in a reference frame which is not in motion with respect to the ground and in a reference frame which moves together with the train. Are these two reference frames inertial? 2. Consider the same train but now assume that when the object is thrown upwards (with same velocity and height as 1.) the train has a negative acceleration A and its instantaneous velocity is V. Determine the horizontal distance from the starting point at which the object falls on the floor of the carriage. Describe the motion in the two reference frames of problem 1. Are they inertial in the present case? I'd appreciate any help/advice. Thanks in advance.