Question

1. during a car collision test, two crash test dummies are given a velocity of 27 m/s, and then brought to a stop. dummy jimmy is stopped with a cement wall, while dummy casey is stopped with an airbag. both dummies have the same mass. which dummy has a higher force applied to them?

clear all
dummy casey
they have the same force
dummy jimmy
they have no force applied

Explanation:

Step1: Use the formula \(F = ma\) and \(v^{2}=u^{2}+2as\) (where \(v = 0\), \(u = 27m/s\)) to get \(a=-\frac{u^{2}}{2s}\). Then \(F=-m\frac{u^{2}}{2s}\). Since \(u\) is the same for both dummies. The dummy with smaller \(s\) (stopping distance) will have larger \(|F|\).

Step2: A concrete wall has a smaller stopping distance than an airbag. So Dummy Jimmy (stopped by concrete wall) has a larger force.

Answer:

Dummy Jimmy