1. ## physics

A person drops a ball in a train traveling along a straight, horizontal track at a constant velocity. What would the person in the train say about the horizontal forces acting on the ball?

a. There are no horizontal forces acting on the ball.
b. There is a fictitious (inertial) force acting forward.
c. There is a fictitious (inertial) force acting backward.
d. There is a centrifugal force.

2. ## Re: physics

Originally Posted by Louisana1
A person drops a ball in a train traveling along a straight, horizontal track at a constant velocity. What would the person in the train say about the horizontal forces acting on the ball?

a. There are no horizontal forces acting on the ball.
b. There is a fictitious (inertial) force acting forward.
c. There is a fictitious (inertial) force acting backward.
d. There is a centrifugal force.
what do you think, and why?

3. ## Re: physics

Hmm, I can repeat my spiel about the "throwing force"... Recall the first and second Newton's laws and take into account that a train traveling at a constant velocity is an inertial reference frame, where the Newton's laws hold.

4. ## Re: physics

I would say that it moves forward

5. ## Re: physics

no force acting on it

6. ## Re: physics

the person on the train would see the ball fall straight down from his frame of reference.

7. ## Re: physics

no force would be acting on it if a person on a train would see it, but really it would move forward?

8. ## Re: physics

Originally Posted by Louisana1
no force would be acting on it if a person on a train would see it, but really it would move forward?
You are right about the force. When you say "it would move forward," you mean with respect to which frame of reference: the train or the track?

9. ## Re: physics

What would the person in the train say about the horizontal forces acting on the ball?

10. ## Re: physics

You might also ask what an observer on the ground would say about horizontal forces acting on the ball as it drop. He'd have the same answerto this as the observer on the train.

11. ## Re: physics

So is the correct answer (a) ??

12. ## Re: physics

Perhaps if the ball on the train dangles from a string and the string is cut it is more obvious to any confused students that there is no sideways force?

I read emakarov's Meowton post. I hope that one day I too am so confident that I'm respected that I can talk nonsense without being afraid that people will think I'm an idiot.

13. ## Re: physics

Originally Posted by a tutor
Perhaps if the ball on the train dangles from a string and the string is cut it is more obvious to any confused students that there is no sideways force?

I read emakarov's Meowton post. I hope that one day I too am so confident that I'm respected that I can talk nonsense without being afraid that people will think I'm an idiot.
^^ Me too
It was funny..

14. ## Re: physics

Originally Posted by puresoul
So is the correct answer (a) ??
yes