P18: A nonlinear spring model could include a cubic term. That is, the force is approximated by F(x) = –kx + k’x3 . a) If all quantities are in our usual (SI) units, what are the units of k and k’? b) For a particular spring, the constants are k = 300 and k’ = 5x104 . How much does the potential energy in the spring change when it is stretched from x = 0.02 m to 0.05 m?

In a heat engine if 1000 j of heat enters the system the piston does 500 j of work, what is the final internal energy of the system if the initial energy was 2000 j? 1. write the equation 2.list out your known variables 3.plug the numbers into the equations 4.solve 5.write your solution statement that includes initial energy and final

The frequencies refer to the sample data collected from a population of interest when performing a hypothesis test comparing two or more population proportions.

The electric field between square plates of a parallel-plate capacitor has magnitude e. the potential across the plates is maintained with constant voltage by a battery as they are pulled apart to twice their original separation, which is small compared to the dimensions of the plates. the magnitude of the electric field between the plates is now equal to a)e b)e/4 c)e/2 d)4e e)2e