Please be as detailed as possible. I want to understand how to derive the answer
ID: 1445297 • Letter: P
Question
Please be as detailed as possible. I want to understand how to derive the answer.
A uniform bar has mass 0.0140 kg and is 30.0 cm long. It pivots without friction about an axis perpendicular to the bar at point a in (Figure 1). The gravitational force on the bar acts in the -y-direction. The bar is in a uniform magnetic field that is directed into the page and has magnitude 0.300 B What must be the current I in the bar for the bar to be in rotational equilibrium when it is at an angle 55. n above the horizontal? Use the fact that r = 1/2 IBL^2 for a uniform bar of length L earring a current I in a magnetic field B. Express your answer with the appropriate units.Explanation / Answer
Torque due to gravitational force at the centre of the rod = T1 = mg(L/2)*cos(theta)
T1 = 0.014*9.8*0.15*cos55 = 0.0118 Nm
Also torque = T2 = 0.5*I*B*L^2 = 0.5*I*0.3*0.30^2 = 0.0135*I Nm
Now T1 = T2 =======> 0.0135*I = 0.0118
Current = I = 0.874 A