As my current day job (really afternoon and evenings) I tutor high school and college students in math and science. I was working a problem recently and came up with an answer that didn't agree with the book. After checking my calculations several times, I decided to send it off to my sons Richard and David. Within an hour they had worked the problem and emailed the results back to me. They agreed with me. The interesting thing is that the book answer results from a major rookie error in the force diagram of the roller coaster car. Interesting. I find errors every once in a while in the text books. For the most part; however, they are correct. Now you are wondering why I didn't send it to Robert as well. The answer is quite simple: I don't know why. How's that for an answer?
Part a. is a trick question. No car has a mass, as all cars are amoral. Only people (mostly Catholics) have a mass, and most masses are held on Sundays.
Yes, he is. That is because he bought an engagement ring and is now shoeless and living on Ramen soup and peanut butter sandwiches. Life is so tough for him that he is now drinking Rebel Yell, just like me. Retirement lowers your standards.