Hello, I have some resources to share with you to help inspire you in completing your assignment.
First, the "Applications and Influence" section of the Wikipedia page on Physics shows and mentions a few machines within the field: http://en.wikipedia.org/wiki/Physics
That page also gives an overview of all the different disciplines or research fields within physics, which could help you narrow your focus based on the area that most interests you. Re-visit these concepts in your physics textbook as well.
Physics is just how the physical world interacts with itself and the living world: motion, collisions, forces, etc. My favorite "physics" machine would be the braking system. It causes a large body in motion (like a car) moving at a given speed (any speed will do, as long as it it not sitting still), and applies a force (the brakes) that allow the object to come to a rest (stop moving). Personally, I like how they use that to make roller coasters: without breaks, the ride would never end and the lines are long enough as it is!