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Two blocks on a plane connected with a Rod

  • #1
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Homework Statement


Two blocks m1 and m2 are connected by a weightless rod are on a inclined plane of ∅=37° and μ =0.25 .What is the common accelation and Tension of rod if m1 is 4 kg and m2 is 2 kg such that the 4kg block is the upper block.
OPTIONS

A =4m/2 T=0
B =2m/2 T=5N
C =
10m/2 T=10N
D = 15m/2 T = 9N

Homework Equations


F=ma

The Attempt at a Solution



Looking at m1

T + m1gsinø - friction1 =ma
T +m1gsinø -μm1gcosø =m1a.....

Looking at m2
m2gsinø - T - μm2gcosø =m2a......[II]


Adding I and II

i got a =5m/s2 which is WRONG. :(
[/B]
 
Last edited:

Answers and Replies

  • #2
Merlin3189
Homework Helper
Gold Member
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" Adding I and II " seems to cover a lot of maths! So I don't know what you did there.

But, how about trying the problem without the rod first? What is the acceleration of each block then?

Edit: (Gallileo might have been able to help you with this problem.)
 
  • #3
113
34
" Adding I and II " seems to cover a lot of maths! So I don't know what you did there.

But, how about trying the problem without the rod first? What is the acceleration of each block then?

Edit: (Gallileo might have been able to help you with this problem.)
Hold on gimme a min i'll just do that

Ps - Gallileo as in the actual gallileo or a user called Ga....eo ???? Cuz the actual one...is...well...asleep.And i cant seem to wake him up !
 
  • #4
113
34
" Adding I and II " seems to cover a lot of maths! So I don't know what you did there.

But, how about trying the problem without the rod first? What is the acceleration of each block then?

Edit: (Gallileo might have been able to help you with this problem.)
Wonderful !

UR A GENIUS !!!
I got accelaration is 4 m/s^2 for both block ....and if i look at the option in the question A =4m/2 T=0 it makes sence as tension in the rod should be Zero because they both mobing with same accelaration hence there is no need for tension to appear.

But....why didnt i get it previosly.

Ill try it again with the rod in question
 
  • #5
113
34
A
Wonderful !

UR A GENIUS !!!
I got accelaration is 4 m/s^2 for both block ....and if i look at the option in the question A =4m/2 T=0 it makes sence as tension in the rod should be Zero because they both mobing with same accelaration hence there is no need for tension to appear.

But....why didnt i get it previosly.
Ill try it again with the rod in question
OH...MY....GOD
I realised my error which i did Thrice.

Apparantly m1 + m2 = 2m1

Oh my god how can i be so stoopid !!!!

Thank you so much Merlin.
Thou Truly art as wise as the legends doth proclaim !
 
  • #6
Merlin3189
Homework Helper
Gold Member
1,521
631
Thanks. It's the dead one! He decided that objects fell with the same acceleration whatever their mass and supposedly dropped two cannon balls off the tower at Pisa to prove it. By extension, two blocks sliding down an incline should have the same acceleration, if all other factors like friction are the same.
So I just picked the answer with 0 tension and then tried to get the acceleration to come to 4 m/s^2. (by making g=10 m/s^2)
 
  • #7
113
34
T
Thanks. It's the dead one! He decided that objects fell with the same acceleration whatever their mass and supposedly dropped two cannon balls off the tower at Pisa to prove it. By extension, two blocks sliding down an incline should have the same acceleration, if all other factors like friction are the same.
So I just picked the answer with 0 tension and then tried to get the acceleration to come to 4 m/s^2. (by making g=10 m/s^2)
The bodies of The Wise have long turned to dust
But their wisdom rise from their ashes
Like a phoenix.
 

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