A picture hangs motionless on a wall as shown in Figure 8.7a. If the picture has a mass of \(3.0 \mathrm{~kg}\), what are the magnitudes of the tension forces in the wires?

THINKING IT THROUGH. Since the picture remains motionless, it must be in static equilibrium, so applying the conditions for mechanical equilibrium should give equations that yield the tensions. Note that all the forces (tension and weight forces) are concurrent; that is, their lines of action pass through a common point, the nail. Because of this, the condition for rotational equilibrium \(\left(\Sigma \vec{\tau}_{i}=0\right)\) is automatically satisfied. With respect to the axis of rotation, the moment arms \(\left(r_{\perp}\right)\) of the forces are zero, and therefore the torques are zero. Thus, only translational equilibrium needs to be considered.

Transcribed Image Text:

T2 8-45 02=50/ (a)