Incline with friction and two blocks

AI Thread Summary
The discussion revolves around calculating the acceleration of a block on an incline with kinetic friction and the tension in the string connecting two blocks. The coefficient of kinetic friction is given as 1/6, and the mass of the block is 2.5 kg, with gravity set at 10 m/s². A participant initially calculated the acceleration as -3.7 m/s² but later realized the need to adjust the signs for the tension force and the weight component acting down the incline. There is a consensus that the orange block accelerates down the incline while the green block moves upward. Ultimately, the participant confirmed their understanding of the system's dynamics shortly after the discussion.
SakuRERE
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Homework Statement



The coefficient of kinetic friction between the block of mass m1 = 2.5 kg and the plane in Fig. 6 below is 1/6. Find (a) the acceleration of the block and (b) the tension in the string. Take g = 10 m/s2.
upload_2018-10-15_2-3-47.png


Homework Equations


Fnet=ma

The Attempt at a Solution


please i don't know what is the mistake here. the answer should be: a=2m/s^2 .
by the way i am assuming that the orange block is accelerating to the left down across the incline and so the green block up
this is my attempt :
upload_2018-10-15_2-5-11.png
 

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SakuRERE said:

Homework Statement



The coefficient of kinetic friction between the block of mass m1 = 2.5 kg and the plane in Fig. 6 below is 1/6. Find (a) the acceleration of the block and (b) the tension in the string. Take g = 10 m/s2.
View attachment 232186

Homework Equations


Fnet=ma

The Attempt at a Solution


please i don't know what is the mistake here. the answer should be: a=2m/s^2 .
by the way i am assuming that the orange block is accelerating to the left down across the incline and so the green block up
this is my attempt :
View attachment 232187
i got a=-3.7 m/s^2
 
I would change the sign of the tension force and the weight (mgsin(theta)) of block 1. Usually "up" the ramp is defined as positive.
 
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osilmag said:
I would change the sign of the tension force and the weight (mgsin(theta)) of block 1. Usually "up" the ramp is defined as positive.
do you mean that the system will move up right? like hanging block would go down
 
SakuRERE said:
do you mean that the system will move up right? like hanging block would go down

Compare the force of gravity on block 2 to that on block 1 when block 1 is on the ramp. Block 2 should go down.
 
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osilmag said:
Compare the force of gravity on block 2 to that on block 1 when block 1 is on the ramp. Block 2 should go down.
Thanks i got it just few seconds before you reply :smile:
 
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