The scientific study of earthquakes and seismic waves is called seismology, making option B correct.
968
In a sonometer experiment the bridges are separated by a fixed distance. The wire which may be slightly elastic emits a tone of frequency n when held by a tension T. Tension is increased to 4T; the tone emitted by the wire will be of frequency
For a stretched string frequency scales as sqrt(T), so increasing tension by factor 4 multiplies frequency by sqrt(4)=2, giving 2n.
969
In the sonometer experiment, a tuning fork of frequency 256 Hz is in resonance with 0.4 m length of the wire when the iron load attached to the free end of the wire is 2 kg. If the load is immersed in water the length of the wire in resonance would be (specific gravity of iron = 8).
Apparent weight becomes 7/8 of original so T' = (7/8)T; to keep same frequency L ∝ √T, so L2 = 0.4√(7/8) ≈ 0.37 m.
970
A marine survey ship sends a sound wave straight to the seabed. It receives an echo 1.5 s later. The speed of sound in seawater is 1500 m s^-1. How deep is the sea at this position?
