Fill in the blank with the correct word.Do you know that light travels at a/an …………… of 186000 miles a second?

The correct word to fill in the blank is "speed."

The sentence would read: "Do you know that light travels at a speed of 186,000 miles a second?"

This is a well-known fact in physics, as the speed of light in a vacuum is approximately 299,792 kilometers per second, which is commonly rounded to 186,000 miles per second when expressed in imperial units. The concept of speed is crucial in understanding various phenomena in physics, including the behavior of light and the principles of relativity. The speed of light is considered a universal constant and is essential in calculations related to space, time, and the fundamental laws of nature.