An ultrasonic tape measure uses frequencies above 20 MHz to determine dimensions of structures such as buildings. It does this by emitting a pulse of ultrasound into air and then measuring the time for an echo to return from a reflecting surface whose distance away is to be measured. The distance is displayed as a digital read-out. For a tape measure that emits a pulse of ultrasound with a frequency of 22.0 MHz,
(a) What is the distance to an object from which the echo pulse returns after 24.0 ms when the air temperature is 26°C?
(b) What should be the duration of the emitted pulse if it is to include 10 cycles of the ultrasonic wave?
(c) What is the spatial length of such a pulse?