Geologists use the Mohs Harness Scale (aka the Scratch Test) to determine the hardness of a mineral.
For more info, check out http://geology.com/minerals/mohs-hardness-scale.shtml
Answer:
<em>The best explanation is that the first person is grounded to the earth, and his/her body either draws up negative charges from the earth, or tend to conducts negative charges to the earth, depending on the charge on the balloon.</em>
Explanation:
The earth is an infinite store for charges. In the first case where the second person brings a negatively charged balloon towards the first person, the negative charges on the balloon induces the first person's body to tend to attract the negative charges on the balloon through the first person's body to the positive charges within the earth. In the second case when again a positively charged balloon is brought near the first person's hair, the positive charges on the balloon induce the first person's body into drawing up negative charges from within the earth. This charges, and their opposite induced charges, create an attractive force between the hair strands and the balloons.
A goal is scored soccer when the ball crosses the goal line. That is the basic rule in obtaining points in a soccer game. However, there could be circumstances where the referee has the call to determine whether a point is made.
