13 microseconds is the round-trip travel time for sound to travel how many centimeters in soft tissue?

13 microseconds is the round-trip travel time for sound to travel how many centimeters in soft tissue?

• A. 0.5 cm
• B. 1 cm
• C. 2 cm
• D. 5 cm

Answer: (B)

Relate round-trip time to distance using the speed of sound in soft tissue. The sound needs to travel to the reflector and back, so the total time t satisfies t = 2d / c, where d is the one-way distance and c is the speed of sound in tissue (about 1540 m/s). Therefore d = c × t / 2. Plugging in t = 13 microseconds (13 × 10^-6 s) and c ≈ 1540 m/s gives d ≈ 1540 × 13e-6 / 2 ≈ 0.010 m, which is about 1 centimeter. This also checks out with the quick intuition that one-way 1 cm takes roughly 6.5 μs, so a round trip is about 13 μs.

Relate round-trip time to distance using the speed of sound in soft tissue. The sound needs to travel to the reflector and back, so the total time t satisfies t = 2d / c, where d is the one-way distance and c is the speed of sound in tissue (about 1540 m/s). Therefore d = c × t / 2.

Plugging in t = 13 microseconds (13 × 10^-6 s) and c ≈ 1540 m/s gives d ≈ 1540 × 13e-6 / 2 ≈ 0.010 m, which is about 1 centimeter. This also checks out with the quick intuition that one-way 1 cm takes roughly 6.5 μs, so a round trip is about 13 μs.