A ruler stands vertically against a wall. It is given a tiny impulse at such that it starts falling down under the influence of gravity. You can consider that the initial angular velocity is very small so that . The ruler has mass 250 g and length 30 cm. Use m/s for the gravitational acceleration, and the ruler has a uniform mass distribution. Note that there is no friction whatsoever in this problem. (See figure)
(a) What is the angular speed of the ruler when it is at an angle ? (in radians/sec)
unanswered
(b) What is the force exerted by the wall on the ruler when it is at an angle ? Express your answer as the x component and the y component (in Newton)
unanswered
unanswered
(c) At what angle will the falling ruler lose contact with the wall? ( ; in degrees) [hint: the ruler loses contact with the wall when the force exerted by the wall on the ruler vanishes.]
omega= sqrt(2*g*(1-cos(theta)/L)
Mention in comments if answer is correct!
surely wrong !!!
I meant
omega= sqrt((2*g)/L)*(1-cos(theta))
omega= sqrt(3*g*(1-cos(theta))/L)
and for friction both mg component and centripetal component is to be added??
Any one know how to do b and c??
Hello 801x-ers!
I would like to give you a little clue to solve the problem. When we say "the ruler loses contact with the wall when the force exerted by the wall on the ruler vanishes" means that Fx equals zero.
Good luck.
apply conservation of energy:
U=m*g*hcm
EK= 1/2*I*w^2, I=1/3*m*L^2
Eini= mg(L/2) + 0
Efin= mg(L/2)cos30 + 1/2*I*w^2
solve for Eini=Efin -> w=
any one knows how to aswer the other questions?