Cau11:

a)

Van Toc goc

Khi dia quay 1 goc teta thi dong nang la Iw^2/2 voi I = 3mR^2/4

the nang la mgR(1+cosa)/2

Theo DL bao toan Co nang

mgR=Iw^2/2 + mgR(1+cosa)/2

w=can(4g(1-cosa)/3R)

b)

Gia Toc Goc

beta = dw/dt = can(4g/3R)d(Can(1-cosa))/dt

beta= can(4g/3R)sinteta.dteta/(dt.2can(1-costeta))

= can(4g/3R).(sinteta/2 )(w/(can(1-cosa))

=[ 2g.sin(teta/2)]/3R

c)

Momen dong luong

L=Iw=(3mR^2)/4.(can(4g(1-costeta)/3R)

o vi tri thap nhat teta =pi

L= mR^2(can(3g/2R)