A steel rod rigidly clamped at one end free at the other has longitudinal stationary waves set up in it and it vibrates in a mode in which there are eight displacement nodes other than the rigid end. The Young’s modulus for steel is 2.0 × 1011 Pa and its density is 7.8 × 103 kg m–3. The frequency of the source that sets the longitudinal waves in the rod is 10 kHz. The length of the rod is
1
1.2 m
2
2.1 m
3
0.6 m
4
3.2 m