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

Incline with friction and two blocks

  • #1
66
5

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
 

Attachments

Answers and Replies

  • #2
66
5
i

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
 
  • #3
osilmag
Gold Member
124
30
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.
 
  • #4
66
5
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
 
  • #5
osilmag
Gold Member
124
30
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.
 
  • #6
66
5
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:
 

Related Threads on Incline with friction and two blocks

Replies
4
Views
14K
Replies
4
Views
12K
  • Last Post
Replies
2
Views
3K
Replies
2
Views
1K
  • Last Post
Replies
6
Views
11K
  • Last Post
Replies
1
Views
3K
  • Last Post
Replies
3
Views
2K
  • Last Post
Replies
1
Views
2K
Replies
8
Views
3K
Top