mPEC Forum

ถามโจทย์ปัญหา => ถามโจทย์ปัญหากลศาสตร์ => Topic started by: peem on July 09, 2011, 12:28:44 PM



Title: โจทย์ทุนญี่ปุ่น
Post by: peem on July 09, 2011, 12:28:44 PM
A point object of mass m is connected to an inertialess string of length L, the other end of which is connected to a fixed point O. At time t=0, the object is assumed to move horizontally in a vertical plane from the bottom point A (OA=L). in the clockwise direction with an initial speed v0 as seen in the figure.
If √2gl<v0<√5gl, then at a point B (the angle between OB and the horizontal direction is designated θ) the magnitude of the force acting on the object from the string becomes zero, where OB=L and the velocity is perpendicular to OB. v being the magnitude of the vector velocity. If 0<θ<pi
1) the speed v is given by....?

2) the initial speed is ....?

3) From the point B, for a while, the object takes a parabolic orbit till C where OC=L . The maximum elevation (with respect to location B) is expressed as ....?

4) In the case θ=pi/3, the angle ϕ measured as in fig. specifying the point C becomes. .....?

5) and finally the angle , the angle between the object velocity at the point C and the horizontal direction is ...?
ช่วยทำข้อสี่กับห้าทีครับ >:A >:A



Title: Re: โจทย์ทุนญี่ปุ่น
Post by: peem on July 10, 2011, 09:54:47 PM
ช่วยทำหน่อยเถอะครับ >:A