Why does Kant think that happiness is not the object of ethics? Why does he think that ethics concerns obligations/duty rather than human happiness?

Answer each question as thoroughly as possible and provide examples to illustrate each point. Include word count.
Questions:
(1) Why does Kant think that happiness is not the object of ethics? Why does he think that ethics concerns obligations/duty rather than human happiness? (350-500 words)
(2) Using an example, please explain the categorical imperative. What is the categorical imperative? What is the difference between doing something in accordance with duty and acting for the sake of duty? Please try to show how Kant would have applied his categorical imperative to resolve the Trolley Problem. For this question, you will need to watch the short documentary on the Trolley Problem above. (350-500 words)
(3) How do you think Kant would have approached the death penalty? Would he have been in favour or against the death penalty? (350-500 words)
As the bookstore was having trouble acquiring the textbook, some of you may not have it yet. If this is the case, please use this version, reading the preface and chapter 1. (The PDF is attached)

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