Comments on activity
In the first part, you might have found that the table-tennis ball did not move exactly in a straight line. This might happen if the surface was not level, or if either the ball or the table were not completely smooth. If you inadvertently spun the ball, and there was some friction between the ball and table, that would also drive it into a curved path.
In the second part, the cork flies off in the direction it was heading, and falls in a curved path towards the Earth. It is being pulled downward by gravity. If there was no gravity it would move horizontally in a straight line.