Homework Help: Kind of a challenge(for me i guess)

1. Jul 6, 2006

wicked

hello everyone , im a newbe here ,im a dentistry student ,foundation year ,to pass this year im required to pass physics ,i actualy suck at physics lol ,well i need any of you to solve this exam for me please it should be eazy for any member here i guess(i heard everyone here is really good) the catch is i need it by tomorow ,so if this is posible its much apreciated ,thanx alot

Last edited by a moderator: Apr 22, 2017
2. Jul 6, 2006

Hawknc

I'm only new here myself, but I'm fairly certain that's not how it works...there's certainly not many people here who will solve a whole exam for you. Are there any specific questions that you're having trouble with?

3. Jul 6, 2006

J77

Indeed, the challenge is yours...

Show some working!

4. Jul 6, 2006

wicked

yea spesific Qs ,

from file 2 , Q8

from multiple choice Q6
^^havin problems with thos ,
thos are the important ones , but ill be glad if u can solve the last Qin file 2

btw , im not doin that just to get the answers , this is just a practic exam ,the real exam is similar 2 it on saturday ,so i actualy need to learn how to get the answers , anyway ill apreciate it if u can solve any of the 3 Q i mentiond up

5. Jul 6, 2006

nazzard

Hello wicked,

as for Question 8 in the second file:

a) well, try to imagine which forces are acting on you right now (probably sitting in a chair), then there is another force which is responsible for the deceleration of the block in your problem.

b) apply the energy theorem

c) start with Newton's second law of motion; I'm not sure why the text states the coefficient of kinetic friction $$\mu_k=0.33$$ while the sketch says $$\mu_k=0.30$$

Regards,

nazzard

Last edited: Jul 6, 2006
6. Jul 6, 2006

wicked

thats just a printing mistake , thanx alot

7. Jul 6, 2006

wicked

but i dun get it in part A i need s to solve the prob ,and in part C they are askin me for s

8. Jul 6, 2006

nazzard

You're welcome! Feel free to post your results. Then on to the next question!

A small hint: the block has a certain kinetic energy at the bottom of the ramp before it enters the rough part. After the process of deceleration the block does not move, hence the kinetic energy is zero at the end. Where did it go?

Last edited: Jul 6, 2006
9. Jul 6, 2006

wicked

turned to potential energy?
(remeber i suck at physics lol)

10. Jul 6, 2006

nazzard

During the process of deceleration (from the bottom of the ramp to point D) the potential energy of the block stays the same.

But keep the potential energy in mind for part b).

11. Jul 6, 2006

wicked

ًًًٍُُW = PE2 - PE1 = mgh2 - mgh1

i need h , i got m and g ofcorse , still confused bout getting W

12. Jul 6, 2006

nazzard

The good thing about potential energy in this problem: you can choose any height as zero-level for it.

I'd suggest setting $$h_1=0\,m$$ in your equation so that $$h_2=h$$ in the sketch.

"Energy conservation" is the key in b)

Right at the moment the block separates from the spring it has a certain velocity $v_1$ and is situated at the height $$h$$. What does that mean for the total Energy (kinetic+potential)? At the bottom of the slope (point B) the total energy is conserved. The block "gained" kinetic energy but "lost" potential energy. It's better to speak of conversion of energy here and in general.

Edit: The forum is quite slow for me today. Sorry if I can't give you an instant reply.

Last edited: Jul 6, 2006
13. Jul 6, 2006

wicked

aa for f u c k's sake can u just post the solution , i need this S#!t for 2moro i cant be discussin one Q the whole night ,gotta do 16 Q

14. Jul 6, 2006

nazzard

Challenges are meant to test us. It's up to you if you want to learn something from it or take the easy route and avoid them at all costs.

Also: I'm sure if you'd be able to solve this specific question, the other ones will appear a whole lot easier in your eyes as they seem to deal with exactly the same basics: Newton's laws and energy conversion.

Last edited: Jul 6, 2006
15. Jul 6, 2006

wicked

fine fine ill do it my self , thanx anyway

peace ,im out

16. Jul 6, 2006

wicked

eazy route , coz this whole physics corse wont do me any good for the rest of my life,i wana be a goddam dentist

17. Jul 6, 2006

wicked

yea ,ill try ..if not fu-ck it ill try to do better on my final
peace out

18. Jul 6, 2006

nazzard

And I honestly wish you the best of luck in becoming a good dentist. Physics might not be "your thing", but please stay open minded to any topics/subjects that might cross your path. It's a good approach for life in general and you don't want to miss the fun parts of it, right?

Regards,

nazzard

19. Jul 6, 2006

wicked

kol 5ara

thanx i will :)