# Thread: Need Physics help pls

1. ## Need Physics help pls

A person drops a ball in train traveling along a straight, horizontal track at a constant velocity of 50 mph. An observer on the ground (that is, standing next to the tracks) would determine that the horizontal velocity of the ball during the fall is

a. zero
b. equal to 50 mph
c. increasing
d. decreasing

2. ## Re: Need Physics help pls

A person would do very well to determine anything in that situation , but if you have to provide an answer then I would guess that an onlooker would see the ball travelling at the same speed as the train, although technically it would be slowing down very slightly.

3. ## Re: Need Physics help pls

Originally Posted by grillage
A person would do very well to determine anything in that situation , but if you have to provide an answer then I would guess that an onlooker would see the ball travelling at the same speed as the train, although technically it would be slowing down very slightly.
Why? Not because of air resistance because the air is moving with the train and so, horizontally, with the ball.

4. ## Re: Need Physics help pls

Good point. So I guess that the answer will be b then.

5. ## Re: Need Physics help pls

Rule of thumb: If a problem does not specifically mention air resistance, you can usually ignore it.

-Dan