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
Messages
68
Reaction score
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

  • upload_2018-10-15_2-3-47.png
    upload_2018-10-15_2-3-47.png
    91.7 KB · Views: 1,244
  • upload_2018-10-15_2-5-11.png
    upload_2018-10-15_2-5-11.png
    48.6 KB · Views: 1,044
Physics news on Phys.org
i
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.
 
  • Like
Likes SakuRERE
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.
 
  • Like
Likes SakuRERE
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:
 
  • Like
Likes osilmag
Thread 'Variable mass system : water sprayed into a moving container'
Starting with the mass considerations #m(t)# is mass of water #M_{c}# mass of container and #M(t)# mass of total system $$M(t) = M_{C} + m(t)$$ $$\Rightarrow \frac{dM(t)}{dt} = \frac{dm(t)}{dt}$$ $$P_i = Mv + u \, dm$$ $$P_f = (M + dm)(v + dv)$$ $$\Delta P = M \, dv + (v - u) \, dm$$ $$F = \frac{dP}{dt} = M \frac{dv}{dt} + (v - u) \frac{dm}{dt}$$ $$F = u \frac{dm}{dt} = \rho A u^2$$ from conservation of momentum , the cannon recoils with the same force which it applies. $$\quad \frac{dm}{dt}...
TL;DR Summary: I came across this question from a Sri Lankan A-level textbook. Question - An ice cube with a length of 10 cm is immersed in water at 0 °C. An observer observes the ice cube from the water, and it seems to be 7.75 cm long. If the refractive index of water is 4/3, find the height of the ice cube immersed in the water. I could not understand how the apparent height of the ice cube in the water depends on the height of the ice cube immersed in the water. Does anyone have an...
Back
Top