Answer:
One possible explanation for the student's observation is that there may be a slow leak in one or both of the tires, causing the air pressure to gradually decrease over time. This could be due to a puncture, a worn-out valve stem, or a loose connection between the tire and the rim.
To test this explanation, the student could try the following steps:
Check the air pressure in the tires using a gauge before and after each ride to determine how quickly the pressure is decreasing.
Inspect the tires visually for signs of punctures, cracks, or other damage. A close examination of the tire surface may reveal the source of the leak.
Apply a soap and water solution to the tire surface and look for bubbles to identify the location of the leak. This can be done by filling a spray bottle with water and a few drops of dish soap, spraying the solution onto the tire, and watching for bubbles.
If a leak is found, the student should replace or repair the damaged tire or valve stem to prevent air from escaping. If the issue persists, the student may need to have the tire and/or rim inspected by a professional bike mechanic to determine the cause of the leak.