Answer:
when the old wooden stiff poles were being used, none of the kinetic energy during the run-up was stored in the pole. With the new fiber glass flexible pole, some of that energy is stored in the flexing of the pole and then released as the pole straightens out at the top of its arc. Where 13 ft was considered an excellent competition vault with the stiff pole, the additional boost from the stored energy in the flex pole has made 17 ft vaults the winning heights.
Explanation:
when the old wooden stiff poles were being used, none of the kinetic energy during the run-up was stored in the pole. With the new fiber glass flexible pole, some of that energy is stored in the flexing of the pole and then released as the pole straightens out at the top of its arc. Where 13 ft was considered an excellent competition vault with the stiff pole, the additional boost from the stored energy in the flex pole has made 17 ft vaults the winning heights.
The flexible fiberglass poles can bend more than wooden ones, before breaking. This meant that fiberglass poles are able to store more energy than wooden ones, and provide an additional increase in height to the vaulter, when the pole straightens out near the top of the vault.
Answer:
the shortest distance to the obstruction is 0.431 m
Explanation:
We can see this system as an air column, where the plumber is open and where the water is closed, in the case when he hears the sound there is a phenomenon of resonance and superposition of waves with constructive interference.
For the lowest resonance we must have a node where the water is and a maximum where the plumber is a quarter of the wavelength
λ = ¼ L
If we are in a major resonance specifically the following resonance. We have a full wavelength plus a quarter of the wavelength
λ = 4L / 3
The general formula is
λ = 4L / n n = 1, 3, 5, 7,…
In addition the wave speed is the product of the frequency by the wavelength
v = λ f
Let's replace
v = (4L / n) f
L = v n / (4 f)
Now we can calculate the depth or length of the air column
If we have the first standing wave n = 1
L = 340 1 / (4 197)
L = 0.431 m
If it is the second resonance n = 3
L = 340 3 / (4 197)
L = 1.29 m
We can see the shortest distance to the obstruction is 0.431 m
four seasons, each lasting for about 21 earth years
summer has sun the entire time, while the winter is in full darkness
spring and autumn have a day night cycle
The answers are as follows:
1. B.
A typical atom is made up of three different particles, which are electron, proton and neutron. The proton and the neutron are located inside the nucleus of the atom while the electron orbit round the nucleus.
2. C
The number of proton in an atom determines the atomic number of that atom. Atom are positively charged particles and they do no participate in chemical reactions. The number of proton of an element remain constant at all time while the number of neutrons and the electrons in the atom may change.
3. B.
The first periodic table was created by Dmitri. He arranged the periodic table in such a way that, elements with similar properties fall into the same column in his periodic table. This was because, he arranged the periodic table on the basis of their physical and chemical properties.
4. A
The elements in the periodic table are arranged in horizontal row and vertical column. The column on the periodic table divides the elements into groups.
A row of element on the periodic table is called PERIOD. For elements on the same period, they have the same number of atomic orbitals.
5. A
Chemical symbol refers to the one or two letters which are used to represent a particular element. Chemical symbols are derived in a variety of ways. The chemical symbols make it possible for one to recognize an element quickly and to write it in an abbreviated form when writing chemical equations.
6. A.
An object is said to be ductile if it can be pulled into a long wire. It refers to an element's capacity to be pulled into a thin wire without the element been deformed. This is one of the properties of metals. Ductability makes it easier for one to work with a metal.
7. C
When metals atoms react with other atoms, the metal atoms lose electrons, this is because, metals usually have a low number of electrons in their outermost shells, which they always preferred to donate in order to achieve octet form.
8. B
Particle accelerator is a machine that accelerate elementary particles to very high energies, thus producing beam of charged particles which can be used for a lot of different purposes.
