Final answer:
A straight line on a speed vs time graph indicates constant speed; however, in activities like running, speed can vary. To convert the running speed of 30 yards in 30 seconds to mph, use the conversion rate of 1 yard/second = 2.045 mph. The calculated speed is approximately 2.0 mph.
Step-by-step explanation:
When we say a straight line between two points on a graph of speed versus time represents a constant speed, it means there is no acceleration or deceleration over the interval being measured. However, in real-life scenarios such as walking or running, a variety of factors like fatigue, terrain, obstacles, and personal ability can cause variations in speed. Now, let's calculate the running speed in miles per hour as per the given scenario.
Since the person ran 30 yards in 30 seconds, the speed in yards per second is:
Speed = distance / time = 30 yards / 30 seconds = 1 yard/second
Using the provided conversion factor, 1 yard/second = 2.045 miles/hour, the calculation yields:
Speed in mph = 1 yard/second x 2.045 miles/hour = 2.045 mph
Therefore, the runner's speed is approximately 2.0 mph, which corresponds to option b) 2.0 mph.