Rotational Mechanics: Find Height of Stick in N Turns

[ARNAV SHARMA]

Homework Statement

A student throws a stick of length l up in the air .At the moment the stick leaves his hand ,the speed of the stick's end is zero.The stick completes N turns just as it is caught by the student at the initial release point . Show that the height to which the centre of mass of the stick rose is h=πNL/4[/B]

The Attempt at a Solution

I assumed the stick will make n/2 revolutions when it reaches the max height and this gave me the angular displacement πnlg through this i found out angular velocity and substituted it in conservation of energy formula . where am i going wrong?[/B]

 

[haruspex]

angular displacement πnlg

That is not an angle.

through this i found out angular velocity

How?

 

[Abhishek kumar]

Homework Statement

A student throws a stick of length l up in the air .At the moment the stick leaves his hand ,the speed of the stick's end is zero.The stick completes N turns just as it is caught by the student at the initial release point . Show that the height to which the centre of mass of the stick rose is h=πNL/4[/B]

The Attempt at a Solution

I assumed the stick will make n/2 revolutions when it reaches the max height and this gave me the angular displacement πnlg through this i found out angular velocity and substituted it in conservation of energy formula . where am i going wrong?[/B]

is h=pi*n*l/4 dimensionally correct?

 

[haruspex]

is h=pi*n*l/4 dimensionally correct?

Yes, both sides are distances.

 

[conscience]

is h=pi*n*l/4 dimensionally correct?

Please explain why do you think it is not dimensionally correct ?

I would suggest you to not post randomly .You should only post if it is helpful or if it adds value to a thread .

 

[Abhishek kumar]

Please explain why do you think it is not dimensionally correct ?

I would suggest you to not post randomly .You should only post if it is helpful or if it adds value to a thread .

I thought that pi*n give angular velocity that's why i asked that.but here n is no turn i confuse this frequency

 

[haruspex]

I thought that pi*n give angular velocity that's why i asked that

π is an angle, n is a number, so πn is an angle.
Generally, angles are not considered to have dimension (but see https://www.physicsforums.com/insights/can-angles-assigned-dimension/).

 

[ARNAV SHARMA]

How can i approach then ?

 

[haruspex]

How can i approach then ?

Suppose the stick is rotating at rate ω.
What is the initial speed of its mass centre?
How long will it take to reach its highest point?