Chapter 7: Questions 1 - 5. Problems 1 - 5
Q7.1
Most materials have equal numbers of positive and negative charges.
Q7.2
Rub the plastic and fur together. Then the fur becomes positive and the plastic negative. Then if the plastic attracts the solid, the solid is positive. If the plastic repels the soloid, the solid is negative.
Q7.3
A positive ion is an atom that has lost one or more electrons compared to its neutral state. It has fewer electrons than protons.
A negative ion has more electrons than the neutral atom. It has more electrons than protons.
Q7.4
Just the nucleus. This is a single proton for the most common form of the hydrogen nucleus.
Q7.5
Both the force of gravity and the coulomb force are proportional to the mass or charge acting and the mass or charge being acted on. Both vary as 1/r2.
However, coulomb forces can be positive or negative, since charges come with two different signts. Masses only attract, as there is no such thing as negative mass.
p7.1
P7.2
P7.3
P7.4
P7.5
