US paper currency has changed greatly over the last 30 years - much more than in the 100 previous years. Why?

Asmall 21 kilogram canoe is floating downriver at a speed of 1 m/s. what is the canoe's kinetic energy?

Aria drove to the store, did some shopping, and then came home. during maria's trip, when was her displacement equal to zero?

Consider an insulating crystal, made up of layers of atoms. what form would you expect the temperature dependence of the phonon heat capacity to approach at extremely low temperatures if the interlayer coupling is i)very strong (rigid coupling), and ii) very weak. explain.