# Curling stone coming to rest - friction

1. May 31, 2010

### ghostbuster25

This is just a revision question for an exam i have in a couple weeks.

I think i kow the answer but just want to double check.

a curling stone is released with an instial speed of 3.1 m/s
the coefficent of sliding friction between the stone and ice is 0.017
What is the distance the stone will come to rest?
A 14m B 19m C 29m D 58m E Impossible to tell without mass

I believe it to be E

IF i did have the mass what equation would i need?
$$\mu$$$$_{}slide$$ * mg ??

Many thanks

Last edited: May 31, 2010
2. May 31, 2010

### proculation

Re: friction

you sure ? If a ton of steel is on a ice and I push it to give it a momentum, will it stop at the same place than a curling stone of 10kg ?

3. May 31, 2010

### proculation

Re: friction

btw it was a joke. You had it almost right :P

coefficient of dynamics friction * Force which equals Mass times Acceleration.

4. May 31, 2010

### ghostbuster25

Re: friction

ok re-looked at it and have decided on D 58m as D=V2/the coefficent of sliding friction * gravity (9.8 m/s)

That look correct?

5. May 31, 2010

### proculation

Re: friction

How can you tell the acceleration ? (which is negative) you conclude it is the gravity ?

6. May 31, 2010

### ghostbuster25

Re: friction

well the equation i have is D=V2/$$\mu$$slide * g

I just put in my values of 3.1 m/s2/ 0.017*9.8 m/s

It gave me an answer of 57.6 which is the same as answer D 58m (2sf)

7. May 31, 2010

### proculation

Re: friction

I already told you you were right.

It's just my way to teach. To make sure you understood and looked at your response again to be sure.

8. May 31, 2010

### ghostbuster25

Re: friction

ha ha oh right, ok thanks
Do you know much about collisions in three dimensions between 2 objects? i.e (vbx,vby)?
:)

9. May 31, 2010

### proculation

Re: friction

It's the same thing then between two objects in 2 dimensions. You just add another dimension.

You seperate the forces in x, y, z instead of only x and y. That's it.

10. May 31, 2010

### ghostbuster25

Re: friction

sorry ive been an idiot, i meant in 2 dimensions.
ill tell you the question....

2 objects with masses A 0.60kg and B 0.45kg are travelling towards one another parallel and anti parallel at uAx 1.5m/s and uBx -2.0m/s
the velocity of A after collision is (0,12)m/s what is (vBx,vBy) of B after collision?

I just cant find in my text how to do it for (x,y)

11. May 31, 2010

### proculation

Re: friction

Hint: 3rd law of Newton.

12. May 31, 2010

### ghostbuster25

Re: friction

so if object A has an opposite but equal in magnitude force on object B when they collide then the force acting on B would be f=ma which would be 0.9N, if i rearrnged to find for v i get v=f/m which gives me 2m/s but as B is travelling at -2m/s it would reusult in 0m/s so B would come to a stand still and have (vBx,vBy) (0,0)m/s

is that sort of the way to go?

13. May 31, 2010

### proculation

Re: friction

You "can" do it that way. But the best way is to go with the 3rd law of newton: the conservation of energy.

Or I may say, the momentum. m1 x v1 = m2 x v2

14. May 31, 2010

### ghostbuster25

Re: friction

yer i was going to ask if there was a better way of doing it. That makes sense :) Thanks