<img src="https://d5nxst8fruw4z.cloudfront.net/atrk.gif?account=iA1Pi1a8Dy00ym" style="display:none" height="1" width="1" alt="" />
You are viewing an older version of this Concept. Go to the latest version.

# Inertia

## The tendency of an object to resist a change in its motion.

Estimated2 minsto complete
%
Progress
Practice Inertia

MEMORY METER
This indicates how strong in your memory this concept is
Progress
Estimated2 minsto complete
%
Mystery in Death Valley

### Mystery in Death Valley

Credit: Jon Sullivan
Source: http://commons.wikimedia.org/wiki/File:Racetrack_playa_sliding_stones_moving_rocks.jpg

Even the name of Death Valley sounds a little creepy. But creepier still is the mystery of the sliding rocks in Death Valley. The picture above shows a rock that slid over the surface of a dry lakebed, called Racetrack Playa. You can see the path the rock took. But how did it move?

#### Amazing but True!

• Believe it or not, rocks that weigh up to several hundred pounds often slide over the ground of Racetrack Playa in Death Valley. To date, no one has actually observed the rocks sliding over the surface. However, many people have observed and photographed the tracks that provide evidence for their movement.
• There are never any animal or human tracks near the rocks. Therefore, people or other animals do not supply the force needed to move the rocks.
• How could such heavy rocks move over the ground on their own? Watch this video to see one hypothesis for the mysterious movement of the rocks in Racetrack Playa:

#### What Do You Think?

1. Describe Racetrack Playa and its climate.
2. What is the “favorite” hypothesis to explain the movement of rocks in Racetrack Playa? What force is responsible?
3. What hypothesis is presented in the video above?
4. What are some problems with the hypothesis presented in the video?
5. What do you think? What causes the mysterious movement of rocks in Racetrack Playa?

### Notes/Highlights Having trouble? Report an issue.

Color Highlighted Text Notes