Plank Movement in Empty Space: Rotate or Move?

[adjacent]

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?

 

[Doc Al]

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.

 

[adjacent]

What do you think? Apply Newton's 2nd law for translation and for rotation.

I don't quite understand that.

 

[WannabeNewton]

Write down $F = ma$ and $\tau = I\alpha$ for the system you drew.

 

[adjacent]

Write down $F = ma$ and $\tau = I\alpha$ for the system you drew.

OMG!What's $\tau = I\alpha$ ?

 

[Nugatory]

OMG!What's $\tau = I\alpha$ ?

Something that doesn't easily hit in google :)
Try googling for "moment of inertia" and "torque"

 

[Doc Al]

OMG!What's $\tau = I\alpha$ ?

See: Newton's 2nd Law: Rotation

 

[adjacent]

See: Newton's 2nd Law: Rotation

I have not heard about anything about the moment of inertia or angular acceleration.Anyways,The plank will rotate,Am I right?

 

[Doc Al]

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.

 

[adjacent]

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?

 

[Doc Al]

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.

 

[adjacent]

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?

 

[Doc Al]

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.

 

[adjacent]

Thank you So much Doc Al