Mathematical modelling is an important skill and mechanics courses are often the first places in which modelling can be explored. These interesting questions will allow you to practice these skills whilst developing awareness of the key concepts of mechanics.
There are several parts to this question. The individual pieces could be used as starters or filler activities for students who finish classwork early. Enthusiastic students might work through them in their own time. Since there is no absolutely 'correct' answer to many of these questions, they might productively be used for discussion: students create their own answers and then explain them to the rest of the class. Does the class agree? Disagree? Is there an obvious best 'collective' answer?
Can students make up similar questions? Can they put any upper or lower bounds on the numbers?
Students might struggle with the 'open' nature of the questions. To begin, they might like to read the Student Guide to Getting Started with rich tasks