A motion sensor acts as a transmitter when it sends out pulses and as a receiver when it listens for echoes. The delay ∆t between sending the pulse and receiving the echo is equal to 8.9 ms. The air temperature is equal to 20º C. Part A What is the distance between the motion sensor and the object?

Question

Jessie Chase

Physics

10 March, 03:10

A motion sensor acts as a transmitter when it sends out pulses and as a receiver when it listens for echoes. The delay ∆t between sending the pulse and receiving the echo is equal to 8.9 ms. The air temperature is equal to 20º C. Part A What is the distance between the motion sensor and the object?

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Answers (1)

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Tessa Quinn · Answer 1

1.526 m

Explanation:

The motion sensor sends sound waves in air which travels at a speed of 343 m per second at 20 degree. If d be the distance of the reflecting object

total distance travelled = 2d

Time taken t = 8.9 x 10⁻³ s

velocity v = 2d / t

343 = 2 d / (8.9 x 10⁻³)

d = 1.526 m