PHYSICS 7E Chapter 15: Chapter 15 Energy Carried By Wave

Response Details:

19eV is energy in electron volts. 1 electron volt is1.6e-19Joules, so for very small energies it is more convenient touse theelectron volt rather than Joules.

From Einstein's equation e=mc*c, the solution you gave hasjustrearranged this to m=e/c*c

Was this what you needed clarification on?

My Response Details:

That is true but does this give the ans. 19 eV/c*c ?

m = e/c*c

m= 1.6 e -19/c*c but this is not = 19??

Sorry this is wrong. I have confused e for energy with eforelectronic charge.

Energy was 10 MeV,so m = 10 e^6/c*c.

This is still not = 19/c*c.

Please show how to get 19/c*c.

Brian.

Hi everyone,
I'm International Students and I have difficault to understand someproblems in physics. I want to do extra work to be ready forMidtearm.
Please if there is any one can help me by showing me how to solveit.
and if u can show me the steps because I will use it asnotes.

1-What are the metric prefixes for ten and tenth?

2-If you multiplied 7774 m by 36 m, how many significant figuresshould you report in your answer?

3-A ball is dropped:
What is its initial speed?
What is the magnitude of its initial acceleration?


4-A jogger jogs two blocks directly north.
(a) How do the jogger's average speed and the magnitude of theaverage velocity compare?
average speed ( ) magnitude of average velocity
(b) If the jogger's return trip follows the same path, how doaverage speed and magnitude of the average velocity compare for thetotal trip?
average speed ( ) magnitude of average velocity



5-A child's cubic play block has a mass of 115 g and sides of 5.2cm. When placed in a bath tub full of water, will the cube sink orfloat?
(sink) or (float)

6-A ball with a radius of 8 cm and a mass of 550 g is thrown into alake. Will the ball sink or float?
(sink) or (float)

7-Persons A and B do the same job, but B takes longer
Who does the greater amount of work?
person A, person B, Or all the same
Who is more "powerful"?
Person A or Person B

8- Which two renewable energy sources depend on the weather?(Select all that apply.)
geothermal
biomass
tidal
solar
wind

9- The two common liquids used in liquid-in-glass thermometers arealcohol (ethanol) and mercury, which have melting points andboiling points of -114°C, 79°C and -39°C, 357°C,respectively.
Which one of these thermometers would be better for low temperaturemeasurements?
(alcohol or mercury)
Which one of these thermometers would be better for hightemperature measurements?
(alcohol or mercury)

10-What determines the phase of a substance? (Select all thatapply.)
humidity
temperature
amount of the substance
pressure


11-What is the difference between a longitudinal wave and atransverse wave?

Longitudinal wave: particle displacement is (---) parallelperpendicular to wave velocity.
Transverse wave: particle displacement is ( ------) perpendicularparallel to wave velocity.

Give an example of a longitudinal wave.
(sound wave in air OR
light wave)
Give an example of a transverse wave.
(sound wave in air Or
light wave)

12-Which end (blue or red) of the visible spectrum has the shorterwavelength?
Which has the lower frequency?

13- How long does the image of a 18-in ruler appear in a planemirror?
Does this depend on the distance the ruler is from themirror?
(Yes OR
No)

14-What optical phenomenon causes soap bubbles and oil slicks toshow colorful displays?

15- Which two particles that make up atoms have about the samemass? (Select all that apply.)
protons
electrons
neutrons

16- Which two have the same magnitude of electric charge? (Selectall that apply.)
neutrons
electrons
protons

17- Name one phenomenon that can only be explained by light havinga wave nature.
polarization
photoelectric effect
acceleration
displacement

18- How are frequency and wavelength of an electromagnetic waverelated?
higher the frequency, longer the wavelength
higher the frequency, shorter the wavelength
the frequency and wavelength are not direclty related


19- What other name is often used to refer to the electron cloudmodel of the atom?
plum pudding model
billiard ball model
quantum model
nuclear model
planetary model


20- What are the names of the elements with the followingsymbols?
(a) Ne
(b) Li
(c) He

21- After 4 half-lives have gone by, what fraction of a sample of aradioactive isotope remains? (Write your answer in fractionform.)


22- What are the most common names for these compounds andions?
(a) N2O
(b) HCl
(c) C2H3O2 ?
(d) PO43-

23- What is the formula for the common household compound known astable salt? (Type your answer using the format CO2 for CO2.)

24- What element has the lowest electronegativity?
What element has the second highest electronegativity?


Give the Stock system name for the following.
(a) Cr(OH)2
(b) CuCl2
(c) AuBr3

The Sun is powered by nuclear fusion. In each chain reaction, four hydrogen nuclei fuse together to become a single helium nucleus. The total combined mass of the individual hydrogen nuclei before the reaction is greater than the mass of the helium nucleus. The mass lost as a result of this chain reaction is turned into energy according to Einstein’s famous equation, E = mc² (Chapter 39). Consider the first part of the chain reaction in which two hydrogen nuclei (each a single proton) fuse. Figure P8.56A shows the potential energy curve of a two-proton system. The energy in this graph is given in keV, where “eV” is the abbreviation for the unit electron-volt and 1 eV = 1.6 × 10−19 J. When the protons are more than about 2 fm (2 × 10−15 m) apart, the potential energy is positive. When the protons are close together, the potential energy is negative, and the protons are fused. Figure P8.56B shows a close-up of the potential energy curve when the protons are far apart.

1. a. What is the minimum mechanical energy required for the two protons to fuse? Give your answer in keV.
2. b. The mechanical energy of an average two-proton system in the Sun is around 2 keV. What is the minimum distance between the protons in such a system?
3. c. Explain why it seems impossible for fusion to take place in the Sun. Note: Of course, fusion must take place in the Sun. Although it seems impossible according to classical mechanics, quantum mechanics (Part VI) makes fusion possible. According to quantum mechanics, the seemingly impossible is merely improbable, and even events with a low probability of occurrence may still happen. Because there are so many protons in the Sun, there is a good chance that at any moment many of them will fuse.