Physical Science 1, Chapter 8 Solutions
1.
Let’s assume the slinky is stretched sideways. Then to produce a longitudinal
wave along a slinky, you move the slinky up and down or side to side. Either
of these is perpendicular to the length of the slinky. To make a transverse
wave, move the end of the slinky forward and back along the length of the
slinky.
3.
Light travels much faster than sound. As a result, you can see distant events
before you can hear them. You can see smoke from the gun before you hear
it. You can sometimes see a bat hit a ball before you hear it, and you see
lightning long before you hear the thunder.
7.
Electromagnetic radiation comes from accelerating charges. (That is they
must have a changing motion.)
9.
Radio waves are electromagnetic waves just like light except that they have
longer wavelengths and lower frequencies. Thus, radio waves move at the
same speed as light.
11.
A sunburn comes from damage to your skin from ultra-violet rays. Ultraviolet light passes through clouds much better than visible light, so it is still
there on a cloudy day and you can still be burned. However, ultra-violet light
can not get through glass, so it can not burn you through glass.
15.
Light reflects from a surface at the same angle it hits at. It appears that angle
comes closest to hitting the number 2 so she will see the number 2.
17.
Refraction makes the fish appear higher in the water than it really is.
Therefore, you must aim a spear below what you see. However, a laser will
be refracted just like the light you are looking at. Therefore, if you aim the
laser directly at the image of the fish it will refract to the fish.
Physical Science 1, Chapter 9 Solutions
1. Certain atoms from the cat (arranged into scent molecules) have fallen from the
cat onto the ground. The dog inhales some of these into its nose and identifies the
atoms (as scent molecules) and can follow the cat.
3. We are constantly exchanging the atoms in our body. We take in and excrete
water, oxygen, and carbon dioxide to name just a few. These same atoms are later
taken into other people’s bodies. Thus, many of the atoms in your body were
once in someone else’s body. And atoms that were once in you are in everyone
else’s body.
7. Only the last one on the far right comes close to representing the size of the
nucleus compared to the size of the atom. The nucleus is roughly 100,000 times
smaller than the atom. We often draw it larger so that we can visualize the
nucleus, but it is in fact tremendously small even compared to the atom.
9. If you start with 16O and take away two protons and two neutrons, you go from 8
protons and 8 neutrons to 6 protons and 6 neutrons. This leaves you with a 12C
atom which is carbon.
11. Even though your body and the chair are mostly empty space, there are forces
between the atoms in your body and the atoms in the chair. These forces hold the
atoms together to make the chair and to make your body. They also prevent the
atoms from falling through each other.
12. The approximate mass comes just from the number of protons plus the number of
neutrons. This is 56 + 43 = 99, or 99 atomic mass units (or 99 grams per mole).
The atomic number is 43 which means the element is Technetium.
13. To be neutral, the atom must have the same number of electrons as protons.
Therefore, since iron has 26 protons it must also have 26 electrons.
17. You can distinguish a sodium vapor lamp from a mercury vapor lamp by looking
at their spectra. That is, you separate the different wavelengths of light and see
which are present.
19. The energy of light is proportional to its frequency. Therefore, blue light, which
has a higher frequency and a shorter wavelength than red light, has more energy
than red light. Since it has more energy, it corresponds to a greater energy
transition.
25. Because the frequency of violet light is about twice the frequency of red light, a
photon of violet light has about twice as much energy as a photon of red light.
E=hf.
27. In the wave model of electrons, the electrons must form standing waves around
their orbits. As a result, only certain sizes and energies are allowed. (There are
only certain standing waves in a system.)