If the wheel of Prob. 3-9 shows resonance at 900 rpm with damping of = 0.10, determine the phase lag of the original unbalance and check the vector diagrams of Probs. 3-9 and 3-10.

Probs. 3.10

If for the same disk of Prob. 3-9, the trial weight of 2 oz is placed at 135° cw from the reference mark, the new unbalance is found to be 4.3 mm at 11 e CW. Show that the correct balance weight is unchanged.

Prob. 3-9

A thin disk is supported on spring-mounted bearings with vibration pickup and strobotac, as shown in Fig. P3-9. Running at 600 rpm ccw, the original disk indicates a maximum amplitude of 2.80 mm at 45° cw from a reference mark on the disk. Next a

trial weight of 2.0 oz is added at the rim in a position 91.5° cw from the reference mark and run at the same speed. If now the new unbalance is 6.0 mm at 80° cw from the reference mark, determine the position and weight necessary to balance the original disk.