(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?
Suppose a bat uses sound echoes to locate its insect prey, 3.00 m away. (a) Calculate the echo times for temperatures of 5.00C and 35.0C. (b) What percent uncertainty does this cause for the bat in locating the insect? (c) Discuss the significance of this uncertainty and whether it could cause difficulties for the bat. (In practice, the bat continues to use sound as it closes in, eliminating most of any difficulties imposed by this and other effects, such as motion of the prey.)
Ex, 27 : What should be the tension applied to a
wire of length 0.8 m and mass 5 gm if it is to
vibrate with a fundamental frequency 100 Hz ?
(a) (i) State what is meant by the specific acoustic impedance of a medium.
(ii) The density of a sample of bone is 1.8 gcm 3 and the speed of ultrasound in the bone is
4.1 x 10°ms-1.
Calculate the specific acoustic impedance Z, of the sample of bone.
Z3 =
kgm-2s-1
Chapter 16 Solutions
Physics for Scientists and Engineers with Modern Physics
Need a deep-dive on the concept behind this application? Look no further. Learn more about this topic, physics and related others by exploring similar questions and additional content below.