Q1. As part of a safety investigation, two 1300kg cars traveling at 18m/s are crashed into different barriers. Find the average forces exerted on

(a) car that hits a line of water barrels and takes 1.8s to stop, and

(b) car that hits a concrete barrier and takes 0.5s to stop.

Q2. The concentration of zinc in a rod of brass is maintained at 10 percent at one end of a rod that is 0.01 m long; the other end is maintained at 0% by vaporizing the Zn as it arrives. At 500°C, the diffusion coefficient of Zn in brass is 4.10-17 m2.s-1. What is the flux of Zn moving down the rod? Write down all your assumptions (hint: you will need to look up the density of copper. You do not require accounting for the variation in density with alloy composition). Give details what the boundary conditions were.