Search
 
 

DYNAMICS - CASE STUDY

    Introduction


Problem Diagram

 

After a particularly long lunch, an employee, in a hurry to return to work, slams his car (Car 1) into his boss's new Mercedes (Car 2), resulting in immediate termination of his employment.

What is known:

  • Car 1 weight w1 = 2,500 lb
  • Car 2 weight w2 = 3,500 lb
  • Car 1 moment of inertia about the CG
       I1-cg = 1,164.6 slug-ft2
  • Car 2 moment of inertia
       I2-cg = 2,101.5 slug-ft2
  • Car 1 velocity v1 = 52 mph
  • Car 2 velocity v2 = 0 mph
  • impact angle α = 45°
  • position vectors for Cars' CGs
    r1/P = (3sinα - 6cosα)i + (6sinα + 3cosα)j ft
    r2/P = -5i - 3j ft
  • coefficient of restitution e = 0.2
     

Problem Graphic
  Question

 

What are the translational and rotational velocities of the two vehicles immediately after the impact? Assume the bodies are perfectly rigid and the impact is elastic.

   
  Approach

 
  • Use the Conservation of Angular and Linear Momentum as well as the coefficient of restitution to determine the velocities of each car.
  • Ignore the friction between the car and the ground.
     
   
 
Practice Homework and Test problems now available in the 'Eng Dynamics' mobile app
Includes over 400 free problems with complete detailed solutions.
Available at the Google Play Store and Apple App Store.