Oscillations and Mechanical Waves
Port-au-Prince Earthquake (Part 1)
Date :
January 2015
Author :
Olivier Tardif-Paradis, Mathieu Riopel
College :
Cégep Garneau
Length :
2 hours
Related concept(s) :
Simple harmonic motion, compound pendulum, resonance
The students have to determine the factors that help a building withstand an earthquake. To do so, they are given a situation drawn from the earthquake in Haiti in 2010. To determine the factors sought, the students have to calculate the building's natural oscillation frequency using Newton's second law. Using a few simplifying assumptions, it is possible to liken a building's oscillation to that of a compound pendulum. In this way, the students will be able to establish the formula for the motion, which corresponds to the differential equation for the simple harmonic motion, and obtain an equation that will allow them to calculate the building's natural oscillation frequency. They then have to make the connection between a system's natural frequency and the phenomenon of resonance that can contribute to the destruction of some buildings.