The constant used in the depth equation to convert go-return time to depth is 1.54 mm per microsecond. Which of the following values is correct?

The constant used in the depth equation to convert go-return time to depth is 1.54 mm per microsecond. Which of the following values is correct?

• A. 1.54
• B. 0.75
• C. 2.0
• D. 1.00

Answer: (A)

Converting go-return time to depth uses a fixed depth-per-time factor. In this context, 1.54 millimeters per microsecond is that factor, and it already accounts for the two-way travel and the propagation velocity being used. So for any go-return time t (in microseconds), the depth in millimeters is simply t × 1.54. For example, a go-return time of 20 μs corresponds to 20 × 1.54 = 30.8 mm (3.08 cm) depth. The value 1.54 is the correct conversion because it pairs the travel time with the appropriate depth scale for the given velocity.

Converting go-return time to depth uses a fixed depth-per-time factor. In this context, 1.54 millimeters per microsecond is that factor, and it already accounts for the two-way travel and the propagation velocity being used. So for any go-return time t (in microseconds), the depth in millimeters is simply t × 1.54. For example, a go-return time of 20 μs corresponds to 20 × 1.54 = 30.8 mm (3.08 cm) depth. The value 1.54 is the correct conversion because it pairs the travel time with the appropriate depth scale for the given velocity.