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

Which block will strike first? Left or right?

  • #1
1.
sAMIP.png

A block of Mass 'm' is connected to another block of Mass '2m' through a weightless pulley by a
weightless inextensible thread of length 2l. The left block(mass=2m) rests on a table at
a distance l from its edge, while the right
block is kept at the same level so that the
thread is unstretched and does not sag, and
then released.

What will happen first: will the left
block reach the edge of the table (and touch
the pulley) or the right block hit the table?

3. Solution Attempt:

This question was in SS Krotov but with equal masses and was solved easily by observing the direction of net force on the system but when I tried to solve the question for unequal masses I was not able to reach any result.

If the masses had been equal then the left block would strike first as the net force on the system is towards the right and at the initial moment the centre of mass of the bodies is on the pulley so the net force towards the right will shift the Centre of Mass to the right and left block will have to reach the pulley first.
But if the left block has mass 2M then the cenCen of Mass is not on the pulley and nothing can be said by reasoning... also on making equations I was getting unable to solve as the I had got non-integrable functions
 

Attachments

Last edited by a moderator:

Answers and Replies

  • #2
berkeman
Mentor
56,850
6,831
Welcome to the PF. :smile:

Can you show us your FBDs and the equation work you have done so far? Also, the surface is frictionless?
 
  • #3
Welcome to the PF. :smile:

Can you show us your FBDs and the equation work you have done so far? Also, the surface is frictionless?
Yes all surfaces are frictionless
 
  • #4
berkeman
Mentor
56,850
6,831

Related Threads on Which block will strike first? Left or right?

Replies
6
Views
6K
  • Last Post
Replies
1
Views
2K
  • Last Post
Replies
13
Views
2K
  • Last Post
Replies
1
Views
3K
  • Last Post
Replies
3
Views
6K
  • Last Post
Replies
6
Views
6K
  • Last Post
Replies
12
Views
4K
  • Last Post
Replies
4
Views
3K
Replies
2
Views
2K
Top