I saw this problem in a book: calculate the sum of the elements of the U4 set.
The answer is 0, the elements of the sets being: 1, i, -1, -i.
My questions is: what's the U set? :confused:
Is it posible that if you trow the ball from the top of the train it will not land in the same place because of the friction with the air?? If yes then I made a mistake because in the train there is no friction with the air on the horizontal movement because the air also travels at 200 mph. I...
You are getting it all wrong, the ball isn't going backwards.
The ball tends to slow down because of its weight, and the speed of the train remains constant at 200 mph. So if you think of a point under the train in the moment when you trow the ball, the ball travels a smaller distance from that...