4.22. Inertia http://www.ck12.org
FIGURE 4.44
Summary
- Inertia is the tendency of an object to resist a change in its motion. Because of inertia, a resting object will
remain at rest, and a moving object will keep moving. - Objects with greater mass have greater inertia.
- To change the motion of an object, inertia must be overcome by an unbalanced force acting on the object.
Vocabulary
- inertia: Tendency of an object to resist a change in its motion.
Explore More
At the following URL, read about inertia and watch the truck-and-ladder animation. Then answer the questions
below.
http://www.physicsclassroom.com/mmedia/newtlaws/il.cfm
- Why does the ladder slide forward off the truck when the truck crashes into the car? How could this be
prevented? - Assume that the truck driver in the animation puts on the brakes just as the truck enters the picture, but the
truck still crashes into the car. Explain how inertia is involved. - What force affects the acceleration of the ladder after it leaves the truck?
Review
- What is inertia?
- How does inertia affect the motion of an object?
- What is the relationship between inertia and mass?
- Jonathan and Cody’s older brother Josh, who is pictured in theFigure4.45, is standing at the top of a half-pipe
at Newton’s Skate Park. Gravity is exerting a downward force on the skateboard, as seen in the picture. Why
doesn’t it tip over the edge and start rolling down the side of the half-pipe?