The King's University
Major Assignment #5

Date Due: December 5, 2017

 

Please do the following questions from your text. Each is worth 6 marks in total and some are easier than others! Show complete solutions and use, where appropriate, the techniques that we developed in class (CoM/CoE diagrams, FBD's, correct notation etc)

N5R.2, N6M.10, N7M.7, N9M.5, N10R.2

General Questions:

  1. Use two different ways to determine the rate at which a cylinder will accelerate down an incline.
    1. Method 1: Use conservation of energy
    2. Method 2: Use Forces and Torques

Each method should give the same result so be sure to demonstrate this! For method 2 be sure to provide a proper FBD and vector equations.
  1. Tires on Passenger Jets (courtesy Thomas Moore)

    The tires on a large passenger jet take a beating each time the jet lands. Consider the following data:
    • plane hits the runway at 60 m/s
    • tires leave a skid mark which suggests that it takes the tire 0.2 s to go from rest to rolling without slipping (assume that the frictional force between the tire and runway is constant)

    Make a number sensible approximations for data not given and estimate what fraction of the work done on the plane goes into thermal energy in the tires. What is the approximate rate at which thermal energy is being created in watts per kilogram as the tires are spinning up.

 
  1. Forces on the Hip

    Standing on 1 leg - Calculate the size of the reaction force R when a 100 kg patient stands on 1 leg. You may click on the image to get a bigger view. As shown, assume that the weight of the leg is 1/7th the weight of the patient.