Physics 241
Major Assignment #2

The following questions are taken from your text.

• Each question is worth 6 marks, partial marks will be awarded as warranted.
• Please show your work and argue answers carefully.
• If you wish to work on this assignment with others, please do so but be sure to identify who you worked with and prepare the final write-up on your own.

Synthetic Questions: C5S.7, C6S.5,C7S.9,C8S.9

Rich Context Questions: C5R.1,C6R.2

General Questions (10 marks)

Imagine a cometary body situated far from earth. Assume it falls directly toward the earth and starts with no appreciable speed. The body is composed of ice and is uniform in composition with a radius of 10 km. Ignore perturbations by the sun or other planets and estimate how fast the body will be moving if it collides with the earth. Plot a graph in EXCEL showing the change in potential and kinetic energy of the body as it moves from "infinity" to the surface of the earth. A 1 megaton nuclear warhead would completely destroy Edmonton. Use the conversion factor 1 megaton equivalent = 4.2 x 1015 J to estimate the explosive yield of the cometary mass. Should we be concerned about this? 5 mark bonus: simulate the fall from infinity of the cometary mass in VPython and plot the graphs in VPython. Also provide final kinetic energy and megaton equivalent in a print statement. You are a gifted lawyer who studied physics before law school and are investigating an accident that occurred in the Rockies on the Canadian National Railroad. On a fall evening in 2013 a railroad car was parked at the top of a steep incline. At the bottom of the incline a car of same mass was parked. The brakeman is adamant that he securely locked the brakes of the car at the top of the incline before leaving at the end of the night shift. In the morning both cars were found coupled together in a lake at the end of the train yard. The foreman dismissed the brakeman charging that he did not lock the brakes, the car rolled down the hill during the night and hence the brakeman was negligent. Your client, the brakeman, swears to you that he had locked the car and that someone must have tampered with the car, released the brake and given it a push. Show that indeed your client's story is plausible and that the police should explore a possible crime. See the diagram below for relevant details.

Date Due: Friday, October 17, 2014