Why Does the Upper Block Fall When Force is Applied Below?

AI Thread Summary
When a force is applied to the lower block in a stack of two blocks with no friction between them, the upper block falls because there is no unbalanced force acting on it to keep it in motion with the lower block. Newton's First Law explains that an object at rest will remain at rest unless acted upon by an external force. Since the upper block does not experience any force from the lower block, it remains stationary while the lower block moves. The discussion emphasizes understanding Newton's Laws to grasp the mechanics of the situation. Ultimately, the upper block's descent is a direct consequence of the lack of friction and the principles of motion outlined by Newton.
Shardul Khare
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When a keep two blocks one over another...And apply a foce on the block which is below...Why does the upper block falls down..Why dosent it move with A? assumin there's no friction between A and B?
 
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Shardul Khare said:
When a keep two blocks one over another...And apply a foce on the block which is below...Why does the upper block falls down..Why dosent it move with A? assumin there's no friction between A and B?
Why do you think? Which of Newton's Laws might apply to this situation?
 
phinds said:
Why do you think? Which of Newton's Laws might apply to this situation?
No idea
 
Well, look at it this way. You are surprised that the upper block falls down when the lower block moves out from under it. Ask yourself why SHOULD the upper block move with the lower block?
 
Shardul Khare said:
No idea

Aren't you being a bit lazy here?

Try this. How about you write down, in this thread, all 3 of Newton's Laws? You may copy that from your text, but better yet, state them in your own words to see if you actually not just read them, but comprehend what they say. Then we can jump off from there.

Zz.
 
First Law states that A body continues to be in motion or at rest until an unbalanced force is acted on it
Second law-sEOCND LAW - f=MA
Third Law: Every action has an equal and opposite reaction
 
Shardul Khare said:
First Law states that A body continues to be in motion or at rest until an unbalanced force is acted on it
Second law-sEOCND LAW - f=MA
Third Law: Every action has an equal and opposite reaction

Now, look at your question, and then look at the First Law. In particular, if there's no friction between A and B, how would the First Law be relevant here?

Zz.
 
The Normal and Mg cancel out,no friction means no other force acting on B,right?
 
ZapperZ said:
Now, look at your question, and then look at the First Law. In particular, if there's no friction between A and B, how would the First Law be relevant here?

Zz.
 
  • #10
Shardul Khare said:
The Normal and Mg cancel out,no friction means no other force acting on B,right?
RIght. And what happens to a body with no force acting on it?
 
  • #11
It remains unaccelerated, So when we apply force on the lower bloack,the upper block will stay where it is and the lower block will mover forward, am i right?
 
  • #12
Shardul Khare said:
It remains unaccelerated, So when we apply force on the lower bloack,the upper block will stay where it is and the lower block will mover forward, am i right?
yes, that's where I was leading you in post #4
 
  • #13
phinds said:
yes, that's where I was leading you in post #4
Thank you :)
 
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