Based on the answers provided, the following corrections need to be made to the 3D object:

1. The second cylinder should be extruded from the bottom of the first cylinder, not the top. This will correct the issue identified in question 3.

2. Adjust the size of the second cylinder to ensure its diameter is half of the first one. This will address the uncertainty in question 4.

3. Increase the length of the second cylinder so that it is five times the length of the first one. This will correct the issue identified in question 5.