Physics · May / June 2025 · Paper 11 · Question 27

A pulse of ultrasound from a sensor is reflected back to the sensor by a crack in a piece of metal and by the bottom surface of the metal. The reflection from the crack is received back at the sensor 1.0 × 10⁻⁵ s after the pulse is sent out. The reflection from the bottom surface is received back at the sensor 1.5 × 10⁻⁵ s after the pulse is sent out. The speed of ultrasound in the metal is 5200 m / s. What is the distance x between the crack and the bottom surface of the metal?

1. A0.013 m
2. B0.026 m
3. C0.052 m
4. D0.078 m

As printed in the paper