• Support PF! Buy your school textbooks, materials and every day products Here!

HELP Tension/Friction Question

  • Thread starter cclawfjj
  • Start date
7
0
A block of mass M resting on a 19.1° slope is shown. The block has coefficients of friction μs=0.788 and μk=0.482 with the surface. It is connected via a massless string over a massless, frictionless pulley to a hanging block of mass 1.86 kg. What is the minimum mass M1 that will stick and not slip?

http://capa.physics.mcmaster.ca/figures/kn/Graph08/kn-pic0836.png [Broken]


In terms of mass 1, following eqn can be written:

m1g sin 19.1 - T - Ff = 0

which can be rewritten as:

m1g sin 19.1 - T - m1g cos 19.1 (friction coefficient) = 0
right? since the object is at rest.
then i found T by equating it to m2g (T = m2g...see the diagram as to why i have donet this)

Hence m1g sin 19.1 - m2g - m1g cos 19.1 (0.788) = 0
and then solved for m1....but im not getting the right answer
I dont understand why my approach is wrong...where did i go wrong here?
 
Last edited by a moderator:

Answers and Replies

7
0
plz help, much appreciated
 
7
0
Plx

im literally bursting into tears right now, plz
this question has been frustrating me for the last couple of days
 
Last edited:
7
0
ppl dont be so cruel, please!!!!!!!!!!11
 
7
0
I've posted my solution and clearly demonstrated my attempt to resolve this question to no avail.

PLZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZ
i beg you, you can have my undying gratitude
 
m1g sin 19.1 - T - Ff = 0
Apparently, you mess up the sign in Ff. When you are pulling the mass 1 uphill with tension T, the friction force shall point to the opposite to T.
 

Related Threads for: HELP Tension/Friction Question

Replies
3
Views
2K
  • Last Post
Replies
1
Views
1K
  • Last Post
Replies
2
Views
1K
Replies
2
Views
2K
Replies
2
Views
462
Replies
3
Views
2K
Replies
5
Views
1K
  • Last Post
Replies
4
Views
3K
Top