Finding sample answers or model solutions for Mechanical Engineering Optional Subject questions can be quite helpful in preparing for the UPSC exam. Here are some ways to find these resources:

1. Online Platforms: There are several online platforms where you can find sample answers and model solutions for Mechanical Engineering Optional Subject questions. One such platform is EduRev, which offers a wide range of study materials, including previous year question papers with detailed solutions. You can search for Mechanical Engineering Optional Subject questions on EduRev and access the relevant resources.

2. University Websites: Many universities and educational institutions have their own websites where they provide study materials and resources for different subjects. You can visit the websites of renowned universities that offer Mechanical Engineering programs and look for sample answers or model solutions for the subject. These resources are often provided by professors or academic departments and can be quite reliable.

3. Online Forums and Discussion Boards: Participating in online forums and discussion boards related to Mechanical Engineering can also help you find sample answers or model solutions. These platforms allow students and professionals to share their knowledge and experiences, and you can often find study materials and solutions to specific questions. Websites like Quora, Reddit, and Stack Exchange have dedicated sections for Mechanical Engineering where you can ask questions and get answers from experts.

4. Study Groups and Peer Networks: Joining study groups or connecting with peers who are also preparing for the UPSC exam can be beneficial. You can discuss and share study materials, including sample answers and model solutions, with each other. This collaborative approach can provide different perspectives and help you understand the subject in a comprehensive manner.

Remember to always verify the credibility of the source before relying on any sample answer or model solution. Additionally, it is essential to understand the concepts and principles behind these solutions rather than simply memorizing them.