Equilibrium of a Block on a Frictionless Table and Wall: An Analysis

  • Thread starter Thread starter e(ho0n3
  • Start date Start date
  • Tags Tags
    Equilibrium
AI Thread Summary
In a scenario involving a block on a frictionless table against a wall, the discussion centers on the forces acting on the block. The free-body diagram indicates that the normal force from the table and the block's weight cancel each other, while the normal force from the wall is questioned. It is concluded that if the wall is vertical and there are no horizontal forces acting on the block, the wall does not exert a normal force on the block. The conversation explores the idea that two bodies can be in contact without exerting forces on each other, particularly in a frictionless context. Ultimately, the analysis suggests that the wall's presence does not affect the equilibrium of the block under these conditions.
e(ho0n3
Messages
1,349
Reaction score
0
There is a table besides a wall (so that one edge of the table is touching the wall). Both wall and table have frictionless surfaces. Say I place a block on the table so that it's touching the wall.

Drawing a free-body diagram depicting the situation gives me three forces: the normal to the table and the weight of the block which cancel out, and the normal to the wall. If the block is in equilibrium then the normal force to the wall is zero. Somehow this is bothering me. Now if the table had a rough surface, then I could say that the normal to the wall and static friction cancel each other out. But if there is no static friction, what happens? Can anybody clarify on this please?
 
Physics news on Phys.org
well, if the wall is straight up and down and everything is at right angles, i see no reason for it to exert any type of a normal force on the block. thus you only have to consider the vertical forces, which cancel.

saw your message on your other thread, no prob.
 
DarkEternal said:
well, if the wall is straight up and down and everything is at right angles, i see no reason for it to exert any type of a normal force on the block. thus you only have to consider the vertical forces, which cancel.
So the wall is not exerting a force and the block and the block is not exerting a force on the wall? So the wall and block are in contact and in perfect harmony!?
 
Why would there be any force between the wall and table? I see no need for the wall to support the table. In fact, if the wall magically disappeared, what would happen? If nothing, then how can the wall even be a factor in the problem?
 
well the normal force stems from the compression of atoms on the surface by the body, because a force on the body transmits this compression to the surface. if there is no horizontal force to compress the wall surface, how can there be a reaction force from the wall?
 
So two bodies can be in contact with each other without exerting forces on each other? OK, I'll buy that.
 
Thread 'Variable mass system : water sprayed into a moving container'

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}...
View full post »

Similar threads

Newton's law problem: Pushing 2 stacked blocks on a horizontal table
Replies
13
Views
3K
Is friction really always related to the normal force?
Replies
5
Views
2K
Friction problem of a block sandwiched between 2 surfaces
Replies
6
Views
1K
How Does Friction Affect the Reaction Force Between Two Blocks?
Replies
3
Views
2K
Static Friction Required to Keep the System from Moving (Two Boxes)
Replies
16
Views
3K
Newton's laws — Two stacked blocks sliding on a frictionless floor
Replies
17
Views
3K
Direction of the normal force when acting on a tilted object
Replies
9
Views
3K
Physics Homework -- block pressed against a wall is sliding....
Replies
4
Views
3K
Finding the work done by a block
Replies
4
Views
3K
Solving a Simple Diff. Eq: Block in a Frictionless Ring
Replies
10
Views
2K

Hot Threads

Recent Insights

Back
Top