Q1. As part of a safety investigation, two 1300kg cars traveling at 18m/s are crashed into different barriers. Find out an 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. Liquid nitrogen has a boiling point of 77.3 K and a latent heat of vaporization of 2.01 105 J/kg. A 60.0-W electric heating element is immersed in an insulated vessel containing 46.5 L of liquid nitrogen at its boiling point. How various kilograms of nitrogen are boiled away in time of 7.50 h?