If dropped separately, the paper flies about. If dropped with the paper on top of the book, they fall at the same rate. Why?

Africtionless piston-cylinder contains 50 l of saturated liquid r-134a. the piston has a mass and an area resulting in an applied pressure of 500 kpa on the refrigerant. the refrigerant is now heated until its temperature rises to 70∘c. calculate the work (in kj) done during this process.

When solid surfaces slide over each other the kind of friction that occurs is called friction

Acar weighs 15,000 n, and its tires are inflated to a pressure of 190kpa. how large is the area of the car's tires that are in contact with the road?