Solve Work on Inclined Plane for m1, a, h, m2, uk

[oreosama]

Homework Statement

A block of mass m1 is placed on an inclined plane with slope angle a and is connected to a second hanging block of mass m2 by a cord passing over a small frictionless pulley the coefficient of kinetic friction is uk the system is released from rest with block m2 dropping a distance h.

given m1, a, h, m2, uk
calc the work due to each of the forces on block 1 in moving h
calc the work due to each of the forces on block 2 in moving h
calc the total work on the sys and final speed of the blocks

Homework Equations

w = F*d

The Attempt at a Solution

http://i.imgur.com/IxtPw.png

for block1

Wg = -h*mg*sin a

Wt1 = hT

Wn=0

Wff = -h*uk*mg*cos a

Wtot = hT - *mg*sin a - h*uk*mg*cos a


for block2

Wg = mgh

Wt = -hT

Wtot = mgh - hT


hT - *mg*sin a - h*uk*mg*cos a + mgh - hT = 1/2*m*Vf^2 + 1/2*m2*Vf^2 - 0 (start from rest)

sqrt( 2/(m1+m2) * (mg*sin a - h*uk*mg*cos a + mgh)) = Vf



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blocks a, b, c are connected as shown. block a,b,c have same mass m and coefficient of kinetic friction between each block and the surface is uk. block c descends with constant velocity. use 30 for angle of incline. given m h uk determine

work due to forces on A moving h
work due to forces on B moving h
work due to forces on C moving h
solve for uk in terms of the other givens for the system to move at constant speed



http://i.imgur.com/DtwxJ.png


block A

Wff= -uk*mg*h

Wt= T1*h

block B

Wt2 = T2*h
Wg = -mg*sin a*h
Wff= -uk*mg*cos a * h
Wt1 = -T1*h

wtot = T2*h - mg*sin a * h - uk*mg*cos a * h - T1* h

block C

Wg = mg*h
Wt2 = -T2*h

Wtot = mg*h - T2*h


T1*h - uk*mg*h + T2*h - mg*sin a * h - uk* mg* cos a * h - T1*h + mg*h - T2*h = 0(constant speed implies vf v0 are the same meaning no change in kinetic energy right??)

-uk*mg*h - uk*mg*cos a * h = mg*sin a * h - mg*h

-uk - uk*cos a = sin a - 1

-uk(1 + cos a) = sin a - 1
uk = - (sin a - 1/ (1+cos a))

uk = 1/2 / (2+sqrt(3))/2

uk = 1/(2+sqrt(3))






want to be sure I am not doing anything horribly wrong thanks for any help.

 

[SammyS]

Homework Statement

A block of mass m₁ is placed on an inclined plane with slope angle θ and is connected to a second hanging block of mass m₂ by a cord passing over a small frictionless pulley. The coefficient of kinetic friction is μ_k. The system is released from rest with block m₂ dropping a distance h.

given m₁, θ, h, m₂, μ_k
calc the work due [STRIKE]to[/STRIKE] by each of the forces on block 1 in moving h
calc the work due to each of the forces on block 2 in moving h
calc the total work on the sys and final speed of the blocks

http://i.imgur.com/IxtPw.png
...

----

blocks a, b, c are connected as shown. block a,b,c have same mass m and coefficient of kinetic friction between each block and the surface is uk. block c descends with constant velocity. use 30 for angle of incline. given m h uk determine

work due to forces on A moving h
work due to forces on B moving h
work due to forces on C moving h
solve for uk in terms of the other givens for the system to move at constant speed

http://i.imgur.com/DtwxJ.png
...

want to be sure I am not doing anything horribly wrong thanks for any help.

Wow! A little bit of punctuation, etc. sure helps ! ...along with a few other changes.

 

[oreosama]

didnt seem to be an issue on other posts, sorry

 

[SammyS]

didnt seem to be an issue on other posts, sorry

Do you mean, in your other posts?

In many of those you did, at least, use periods.

You probably should take a bit of time to read rules for posting in this Forum. Here are two short excerpts.

General Posting Guidelines
...Pay reasonable attention to written English communication standards. This includes the use of proper grammatical structure, punctuation, capitalization, and spelling. ...

Do not hijack an existing thread with off-topic comments or questions--start a new thread.
​

 

[oreosama]

are you having trouble interpreting what I've typed? clearly not or you wouldn't be capable of correcting it by replacing one word and telling me to use more periods. I think that fulfills reasonable english communication.

now read the last sentence of your post. do you not see the irony?