volume_mute

Falling Rock

publish date: 2023/03/11 04:37:00 GMT+11

volume_mute

Consider a falling rock at a time when it is traveling at just less than terminal speed.  Will its acceleration be less than, equal to, or more than 9.8 m/s2 at this time?

less than 9.8 m/s2
equals to 9.8 m/s2
more than 9.8 m/s2

Correct Answer

less than 9.8 m/s2

Explanation

less

When the object finally reaches terminal speed, the air resistance is equal to the rock's weight.  At slightly less than terminal speed, air resistance may be considerable, but it is less than the rock's weight.  The net force on the rock is its weight minus air resistance.  since air resistance is less than the rock's weight, the acceleration must be less than the acceleration of gravity.

Reference

Basic Physics: A Self-Teaching Guide

Quizzes you can take where this question appears