Definitions Only

Question 1

Sound

Answer 1

The periodic variation in pressure, particle displacement or particle velocity in an elastic medium

Question 2

Chokepoint

Answer 2

A geographical feature above or below the surface that restricts the freedom of movement of a submarine

Question 3

Doppler

Answer 3

The apparent change in frequency due to the relative motion of the source and static receiver

Question 4

Limiting ray

Answer 4

By application of the HALT rule, there will be a sound ray, which just grazes, or tangential to a boundary layer.

Question 5

Critical angle ray

Answer 5

Sound ray which strikes a boundary layer at the steepest angle, and still exhibits almost 100% reflection.

Question 6

MDR

Answer 6

Range at which 50% probability of detection from a single sonobuoy

Question 7

Frequency

Answer 7

Number of complete wave cycles in a second

Question 8

TPK

Answer 8

Number of times a shaft needs to turn in one minute to give one knot of speed

Question 9

CSR

Answer 9

Number of times the crankshaft rotated in one second

Question 10

CFR

Answer 10

Number of times an individual cylinder fires in one second

Question 11

EFR

Answer 11

Number of times the engine fires in one second

Question 12

Reduction ratio

Answer 12

The reduction ratio between engine RPM and Shaft RPM through a gearbox expressed as a ratio

Question 13

Harmonic frequency

Answer 13

An echo of a fundamental frequency source

Question 14

Shadow zone

Answer 14

The area in which very little sound energy penetrates

Question 15

Slip rates

Answer 15

Percentage of e every lost form output due to heat/friction on an electrical source