Contents for Newton's Second Law

• Introduction
• Activity 1: Estimating the Mass of a Building
• Activity 2: Calculating Maximum Ground Acceleration

Introduction

Newton's Second Law is directly related to designing buildings that will withstand earthquakes. In designing buildings in earthquake-prone areas, civil engineers are very concerned with the ground acceleration during an earthquake. If a building of mass, m, is speeding up with acceleration, a, during an earthquake, it is subjected to a force given by F=ma and must be built to withstand that force.

Back to Table of Contents

Activity 1: Estimating the Mass of a Building

As a class discussion or with students working in small teams, choose a local building or a famous one, such as the Sears Tower or World Trade Center. Treat estimating the mass of the building as a Fermi problem in which you make reasonable estimates of the components of the problem in an attempt to get an answer to the right order of magnitude.

Back to Table of Contents

Activity 2: Calculating Maximum Ground Acceleration

Collect a sampling of accelerograms (local, large, small, famous, etc) from available sources, such as universities or GNS. The units on the y axis must be in ground acceleration. What was the maximum ground acceleration during each of the earthquakes? Have students calculate the force the building would have to withstand. Try to find accelerograms from an earthquake recorded near and far away from the epicenter to show the students how the acceleration decreases with distance from the source.

Back to Table of Contents