9. What happen the length of an object moving at a significant fraction of the speed of light? A. It increases C. It remains constant B. it decreases D. It becomes zero

The correct answer is B. It decreases.<br /><br />According to the theory of relativity, when an object moves at a significant fraction of the speed of light, its length appears to decrease in the direction of motion. This phenomenon is known as length contraction. The faster the object moves, the more its length contracts in the direction of motion. This means that the length of the object appears shorter than its actual length when it is moving at a significant fraction of the speed of light.