Question

An automatic focus camera is able to focus on objects by use of an ultrasonic sound wave. The camera sends out sound waves which reflect of distant objects and return to the camera. A sensor detects the time it takes for the waves to return and then determines the distance an object is from the camera. The camera lens then focuses at the distance. If a sound wave$(speed=340m{s}^{-1})$ returns to the camera$0.150s$ after leaving the camera, then how far away is the object ?

Answer 1

Step 1: Given:

Speed of sound wave $\left(v\right)=340m/s$

Time $\left(t\right)=0.150s$

Distance of the object $\left(d\right)$

Let the total distance traveled by the sound wave be$D$.

Step 2: Formula

The total distance traveled by the sound wave is given by:

$D=v\times t$

$D=340\times 0.150$

Thus, $D=51m$
The sound wave travels from the camera to the object and then returns back to the camera after reflection.

Thus, $D=2d$

$d=\frac{51}{2}$
$d=25.5m$

Final answer:

The object is 25.5 m away from the camera.