Find Coefficient of Friction for Physics Exam Problem

[arildno]

Secondly, did you regard your acceleration as a POSITIVE or NEGATIVE quantity?

 

[GuruGhulab]

1.25*9.8*sin 35

 

[GuruGhulab]

k, i think made some mistakes, let me so my calculations again, and yea accleration used a positive value.

 

[arildno]

1.25*9.8*sin 35

Indeed, that is valid.
Now provide an answer to my second question.

 

[arildno]

k, i think made some mistakes, let me so my calculations again, and yea accleration used a positive value.

Where is where your flaw lies.

The direction of acceleration is PARALLELL to the direction of tangential gravity, so if you assign negative direction to gravity, you must assign negative direction to acceleration.

The direction of force of friction is ANTI-PARALLELL to the direction of acceleration (trying to reduce acceleration), therefore these two quantities must have opposite signs.

 

[GuruGhulab]

k, some how i got the rite answer, but i m very confused, now, the steps i posted earlier are rite though, rite, ff, fg etc stuff.

 

[GuruGhulab]

you are rite, i made fg positive, Thanks.

 

[GuruGhulab]

Hey thanks a lot arildno, appreciate it man, actully i don even know if ur a man, anywayz whatever u r, thanks a lot, and r u really in Norway ?

 

[arildno]

A word of advice:
Structure your thoughts when doing physics; at the moment, you do not have sufficient control over your mind.

You gain that control by setting up presuppositions in an orderly manner, before attempting to solve a problem.
Also, putting in numerical values is DESTRUCTIVE of orderly, analytical thinking, because you thereby MERGE (unimportant) values from the (all-important) relations/laws into an unimportant decimal number.

It is the RELATIONS between quantities that are important when doing physics, NOT the values of those quantities as such.
Those relations, however, can only be properly stated in ALGEBRAIC form, i.e, with the aid of symbols/letters SIGNIFYING the quantities related to each other.

 

[arildno]

Hey thanks a lot arildno, appreciate it man, actully i don even know if ur a man, anywayz whatever u r, thanks a lot, and r u really in Norway ?

Yes, I am a man.
Yes, I am in Norway.

 

[GuruGhulab]

Thanks, appreciate it. take care, and i m going to try rest of the problems my self now. Bye.

 

[arildno]

Good luck!