(II) A motion sensor can accurately measure the distance d to an object repeatedly via the sonar technique used in Example 16–2. A short ultrasonic pulse is emitted and reflects from any objects it encounters, creating echo pulses upon their arrival back at the sensor. The sensor measures the time interval t between the emission of the original pulse and the arrival of the first echo. ( a ) The smallest time interval t that can be measured with high precision is 1.0 ms. What is the smallest distance (at 20°C) that can be measured with the motion sensor? ( b ) If the motion sensor makes 15 distance measurements every second (that is, it emits 15 sound pulses per second at evenly spaced time intervals), the measurement of t must be completed within the time interval between the emissions of successive pulses. What is the largest distance (at 20 5 C) that can be measured with the motion sensor? ( c ) Assume that during a lab period the room’s temperature increases from 20°C to 23°C What percent error will this introduce into the motion sensor’s distance measurements?
(II) A motion sensor can accurately measure the distance d to an object repeatedly via the sonar technique used in Example 16–2. A short ultrasonic pulse is emitted and reflects from any objects it encounters, creating echo pulses upon their arrival back at the sensor. The sensor measures the time interval t between the emission of the original pulse and the arrival of the first echo. ( a ) The smallest time interval t that can be measured with high precision is 1.0 ms. What is the smallest distance (at 20°C) that can be measured with the motion sensor? ( b ) If the motion sensor makes 15 distance measurements every second (that is, it emits 15 sound pulses per second at evenly spaced time intervals), the measurement of t must be completed within the time interval between the emissions of successive pulses. What is the largest distance (at 20 5 C) that can be measured with the motion sensor? ( c ) Assume that during a lab period the room’s temperature increases from 20°C to 23°C What percent error will this introduce into the motion sensor’s distance measurements?
(II) A motion sensor can accurately measure the distance d to an object repeatedly via the sonar technique used in Example 16–2. A short ultrasonic pulse is emitted and reflects from any objects it encounters, creating echo pulses upon their arrival back at the sensor. The sensor measures the time interval t between the emission of the original pulse and the arrival of the first echo. (a) The smallest time interval t that can be measured with high precision is 1.0 ms. What is the smallest distance (at 20°C) that can be measured with the motion sensor? (b) If the motion sensor makes 15 distance measurements every second (that is, it emits 15 sound pulses per second at evenly spaced time intervals), the measurement of t must be completed within the time interval between the emissions of successive pulses. What is the largest distance (at 205C) that can be measured with the motion sensor? (c) Assume that during a lab period the room’s temperature increases from 20°C to 23°C What percent error will this introduce into the motion sensor’s distance measurements?
Bats of the Vespertilionidae family detect the distance to an object by timing how long it takes for an emitted signal to reflect off the object and return. Typically they emit sound pulses 3.00 ms long and 70.0 ms apart while cruising.
When an object is only 36.7 cm away, how long will it be before the echo is heard?
When a sinusoidal wave crosses the boundary between two sections of cord as in Fig. 11–34, the frequency does not change (although the wavelength and velocity do change). Explain why
A sailor working on boat maintenance while at sea hits the side of his boat with ahammer just below the water line. He hears an echo of the sound reflected from theocean floor, directly below the boat, 2.5 seconds later. How deep is the water at thislocation? Assume the speed of sound in sea water is 1560 m/s and does not vary withdepth.
Chapter 16 Solutions
Physics for Scientists and Engineers with Modern Physics
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