Movement of a plank

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  • #1
adjacent
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Here is a plank in empty space(There are no forces except one) .Someone is pushing it on a side.Will it rotate or Move straight in the direction of the force?
 

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  • #2
Doc Al
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Here is a plank in empty space(There are no forces except one) .Someone is pushing it on a side.Will it rotate or Move straight in the direction of the force?
What do you think? Apply Newton's 2nd law for translation and for rotation.
 
  • #3
adjacent
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What do you think? Apply Newton's 2nd law for translation and for rotation.
I don't quite understand that.:confused:
 
  • #4
WannabeNewton
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Write down ##F = ma## and ##\tau = I\alpha## for the system you drew.
 
  • #5
adjacent
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Write down ##F = ma## and ##\tau = I\alpha## for the system you drew.
OMG!What's ##\tau = I\alpha## ?
 
  • #6
Nugatory
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OMG!What's ##\tau = I\alpha## ?

Something that doesn't easily hit in google :)
Try googling for "moment of inertia" and "torque"
 
  • #9
Doc Al
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I have not heard about anything about the moment of inertia or angular acceleration.Anyways,The plank will rotate,Am I right?
The motion of the plank will be a combination of the translation of the center of mass plus rotation about the center of mass. It will rotate as well as translate.
 
  • #10
adjacent
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The motion of the plank will be a combination of the translation of the center of mass plus rotation about the center of mass. It will rotate as well as translate.
Then where should I apply a force so the plank will only move straight without rotating?On the center of Mass?
 
  • #11
Doc Al
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Then where should I apply a force so the plank will only move straight without rotating?On the center of Mass?
Yes, at the center of mass.
 
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  • #12
adjacent
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When I apply the force on the sides it will rotate and translate,What will happen if I remove the force.Will the plank keep rotating and translating or Move in a constant velocity in a straight line?
 
  • #13
Doc Al
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When I apply the force on the sides it will rotate and translate,What will happen if I remove the force.Will the plank keep rotating and translating or Move in a constant velocity in a straight line?
When you remove the force, the center of mass will continue moving in a straight line at constant speed. And the plank will continue to rotate about its center of mass with a constant angular velocity.
 
  • #14
adjacent
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Thank you So much Doc Al
 

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