What is the displacement of Carlos's end of the spring in a tug of war with Bob?

[cragar]

Homework Statement

The left end of a spring is attached to a wall. When bob pulls on the right end with 200N force,
he stretches the spring by 20cm. The same spring is then used for tug of war between bob and Carlos. Each pulls on the spring with a 200N force. How far does Carlos's end of the spring move? explain

The Attempt at a Solution

If I think of this as the spring hanging in a gravitational field. I put a weight on it that was 200 N it will pull it down 20cm. but if my spring is hanging on a nail, that is also providing a force of 200N in the opposite direction. So i think that the spring will be stretched still by 20cm. Although I am not sure if it will be stretched by 10cm at Carloss's end or zero.

 

[TSny]

Yes, the spring will still stretch a total of 20 cm. I think the two guys are assumed to move equal distances.

 

[pgardn]

Homework Statement

The left end of a spring is attached to a wall. When bob pulls on the right end with 200N force,
he stretches the spring by 20cm. The same spring is then used for tug of war between bob and Carlos. Each pulls on the spring with a 200N force. How far does Carlos's end of the spring move? explain

The Attempt at a Solution

If I think of this as the spring hanging in a gravitational field. I put a weight on it that was 200 N it will pull it down 20cm. but if my spring is hanging on a nail, that is also providing a force of 200N in the opposite direction. So i think that the spring will be stretched still by 20cm. Although I am not sure if it will be stretched by 10cm at Carloss's end or zero.

Maybe you want to do this in the horizontal to make it easier. (No gravity)

Also you might want to ask yourself how hard the wall pulls on the spring before Carlos comes into play.

Oops I see someone has already posted. I will now kindly drop out.

 

[TSny]

Oops I see someone has already posted. I will now kindly drop out.

Hi, pgardn. Don't drop out. The more the merrier!

 

[cragar]

so then each person will move 10cm

 

[PeterO]

so then each person will move 10cm

Probably - but you can certainly be sure the ends of the spring will be 20cm further apart.

The common, incorrect response to this question is that each move 20cm - as I said, and you seem to realize, that answer is incorrect.

 

[TSny]

Probably - but you can certainly be sure the ends of the spring will be 20cm further apart.

The common, incorrect response to this question is that each move 20cm - as I said, and you seem to realize, that answer is incorrect.

I second that.

 

[pgardn]

I was just going to replace the wall with Carlos. And there you have it.

All is in order.

 

[azizlwl]

Using work-energy analysis could also be used.