A radio wave sent from the surface of the earth reflects from the surface of the moon and returns to the earth. The elapsed time between the generation of the wave and the detection of the reflected wave is 2.6444 s. Determine the distance from the surface of the earth to the surface of the moon. Note: The speed of light is 2.9979 × 10⁸ m/s. A)3.7688 × 10⁸ m B)3.8445 × 10⁸ m C)3.9638 × 10⁸ m D)4.0551 × 10⁸ m E)7.9276 × 10⁸ m

Question

Quizplus · Accepted Answer

The distance traveled by the radio wave is twice the distance from the earth to the moon. 
Let x be the distance from the surface of the earth to the surface of the moon.
The total distance traveled is 2x. 
Using the formula: distance = speed x time, we have 
2x = (2)(2.9979 × 10^8 m/s)(2.6444 s) 
2x = 15.8897 × 10^8 m 
x = 7.9449 × 10^8 m 
The distance from the surface of the earth to the surface of the moon is half of x, which gives 
x/2 = 3.9638 × 10^8 m 
Therefore, the answer is C.

A Radio Wave Sent from the Surface of the Earth