An ultrasound pulse is sent out from a sensor, and it is reflected back to the sensor by a crack in a piece of metal and also by the lower surface of the metal. The echo from the crack returns to the sensor $1.0 \times 10^{-5}\,\text{s}$ after the pulse is emitted. The echo from the lower surface returns to the sensor $1.5 \times 10^{-5}\,\text{s}$ after the pulse is emitted. The speed of ultrasound in the metal is $5200\,\text{m s}^{-1}$. Calculate the distance $x$ between the crack and the lower surface of the metal?
- A$0.013\,\text{m}$
- B$0.026\,\text{m}$
- C$0.052\,\text{m}$
- D$0.078\,\text{m}$