Why doesn't static friction move the other object?

[phantomvommand]

Consider a block sitting on top of a table.

When we push the block rightwards, static friction opposes its motion by acting leftwards on the block.

By Newton's 3rd Law, static friction should act rightwards on the table.

There is now a net rightwards force on the table. Why doesn't the table move?

Assume the table is on a frictionless surface.

 

[phinds]

Why doesn't the table move?

Who says it doesn't? Have you TRIED this experiment?

 

[phantomvommand]

Who says it doesn't? Have you TRIED this experiment?

Sorry, I stated my question wrongly.

If we pushed the table (on the frictionless surface) such that it is on the verge of slipping, does the block on the table move?

 

[Dale]

Why doesn't the table move?

Assume the table is on a frictionless surface.

If the table is on a frictionless surface then it does move.

 

[phantomvommand]

If the table is on a frictionless surface then it does move.

Sorry, I stated my question wrongly.

If we pushed the table (on the frictionless surface) such that it is on the verge of slipping, does the block on the table move?

 

[Dale]

You should draw two free body diagrams. One for the block and one for the table. That should make it pretty clear, and will make it easy to solve quantitatively.

 

[phantomvommand]

You should draw two free body diagrams. One for the block and one for the table. That should make it pretty clear, and will make it easy to solve quantitatively.

Wld I be right to say that the object does move?

I ask this because this exam question seems to suggest that the Horse (analogous to the object) can somehow remain on the verge of slipping.

 

[hmmm27]

We assume that the table/tablecloth interface is frictionless.

[edit: Regarding the horse/tablecoth, what kind of friction are we talking about ? ]

 

[phantomvommand]

We assume that the table/tablecloth interface is frictionless.

Which means that the leftward static friction force acts on the table cloth along the Horse/cloth interface?

By N3L, a rightward static friction acts on the horse?

 

[jbriggs444]

If we pushed the table (on the frictionless surface) such that it is on the verge of slipping, does the block on the table move?

Are you pushing the table so that the table is on the verge of slipping against the block?

[Based on the toy horse example, the answer is "yes"]

If the floor is frictionless, this is actually an identical scenario to pushing the block so that the block is on the verge of slipping against the table. You have two objects with a fixed normal force between them and a non-zero coefficient of friction for their mating surfaces. One object is subject to an external force. No other [horizontal] forces are acting.

Similarly, one could place a box of tools in the bed of a pick-up truck and gently accelerate from a red light. Can one maintain a steady acceleration such that the box is always on the verge of slipping toward the rear of the bed?

Can a waitress holding a tray of beer steins keep the tray perfectly horizontal as she moves smoothly across the room to the table of thirsty businessmen, accelerating and then decellerating as she goes?

If you put a coin on top of a textbook, can you keep the book level while moving it back and forth so that the coin stays in place relative to the book? [I tried it 10 seconds ago. Yes, I can]