Read the following case and answer the questions given below:
A SONAR system sends sound pulses towards an underwater object. The reflected sound pulse returns to the source after a certain time. The time taken for the pulse to return is recorded for four trials.
| Trial | Time taken for pulse to return |
| A | \(0.4\ s\) |
| B | \(0.8\ s\) |
| C | \(1.2\ s\) |
| D | \(1.6\ s\) |
Assume that the speed of sound in water is \(1500\ m/s\).
For each trial, remember that the measured time represents the complete journey of the sound pulse—from the SONAR source to the underwater object and back to the source.
1. What is the distance of the underwater object from the SONAR source in Trial A?
2. What is the distance of the underwater object from the SONAR source in Trial C?
3. A student calculates the distance of the object in Trial B as \(1200\ m\) using the equation \(d = vt\). What mistake has the student made?
4. Suppose the SONAR source records a return time of \(2.0\ s\) instead of \(1.6\ s\), while the speed of sound in water remains \(1500\ m/s\). Which conclusion is correct?