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Physics Study Guide Ch. 29-36 + Homework

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3.) What did Rutherford discover about the atomic nucleus?

All of the above. (The mass of an atom is concentrated in a high-density core; The high-density core of an atom is extremely small compared to the size of the atom; The mass of the atom is concentrated in a positively charged core)

10.) Cite a major advantage of fission power. Cite a major drawback.

All of the above. (It eliminates megatons of sulfur oxides, but it risks large releases of radioactivity; It provides plentiful electricity, but it produces weapons-grade plutonium; It eliminates the release of the greenhouse gas CO2, but it produces radioactive waste)

1.) According to Huygens, how does every point on a wavefront behave?

As a source of secondary wavelets

10.) Of all the planets, why is Mercury the best candidate for finding evidence of the relationship between gravitation and space?

Mercury is in the strongest solar gravity of all the planets.

13.) What is the role of neutrons in the atomic nucleus?

Neutrons contribute strong nuclear force attraction without adding in electric force repulsion, so they help hold the nucleus together.

3.) What classical idea about space and time did Einstein reject?

Einstein rejected the idea that space and time are independent.

14.) Does Einstein's theory of gravitation invalidate Newton's theory of gravitation? Explain.

Einstein's theory agrees with Newton's because of the correspondence principle. Einstein's theory reduces to Newton's in the realm in which Newton's had been tested and proved.

HOMEWORK

11.) When does light behave as a wave? When does it behave as a particle?

Light is emitted and detected as a particle and travels as a wave.

12.) What evidence can you cite for the wave nature of particles?

Particles exhibit two-slit interference.

Radioactivity & Rays

RADIOACTIVITY: the particles which are emitted from nuclei as a result of nuclear instability. Because the nucleus experiences the intense conflict between the two strongest forces in nature, it should not be surprising that there are many nuclear isotopes which are unstable and emit some kind of radiation. RAYS: an idealized model of light, obtained by choosing a line that is perpendicular to the wavefronts of the actual light, and that points in the direction of energy flow.

14.) Exactly what is it that "corresponds" in the correspondence principle?

The experimental predictions of a new theory have to match the experimentally verified predictions of the old theory in the domains where the old theory works.

6.) In the equation E = hf, the h is _________.

a proportionality constant

15.) How many frames of reference does the stay-at-home twin experience in the twin trip? How many frames of reference does the traveling twin experience?

Stay-at-home, 1; traveler, 2

9. Control is maintained in a nuclear reactor by control rods that

absorb excess neutrons.

1.) The general theory of relativity focuses on systems that are _________.

accelerated

13.) Gravitational waves are thought to emanate from _________.

accelerating matter

18.) The hypothetical twin trip featured in the book states that a traveling twin would return to her Earth-bound twin _________.

actually younger

5. Quantum uncertainties are most predominant for simultaneously measuring the speed and location of

an electron.

4.) The energy of a photon is directly proportional to its _________.

frequency

7. Which radiation has no association with electric charge?

gamma

22.) A friend is in a spaceship that whizzes horizontally past you at 0.5c. You see the length of the spaceship _________.

half as long as normally

6.) A glass prism separates light into its component colors by the process of _________.

refraction

10. Suppose you and your sister travel at different speeds in space and you note a slowing of her clock. Compared with her clock your sister will notice that your clock runs

slower.

3.) A quantum of light is a _________.

smallest lump of light

Wave-Particle Duality

the concept that all matter and energy exhibit both wave-like and particle-like properties

Simultaneity

the concept that distant simultaneity - whether two spatially separated events occur at the same time - is not absolute, but depends on the observer's reference frame.

6.) Two events that are simultaneous in one frame of reference _________.

may or may not be simultaneous in a frame moving relative to the first frame

13.) The wavelength of a matter wave is inversely proportional to its _________.

momentum

20.) Carbon-14 in the atmosphere is transformed from _________.

nitrogen

8. The natural background radiation we personally encounter is

more than half.

1.) The famous Michelson-Morley interferometer experiment showed that the speed of light was _________.

of the same value in any state of relative motion

14.) The entity that is simultaneously uncertain in Heisenberg's uncertainty principle for momentum is _________.

position

19.) What change in atomic number occurs when a nucleus emits an alpha particle? A beta particle? A gamma ray?

-2, +1, 0

(HW) Chapter 29 Lightwaves

(HW) Chapter 30 Light Emission

(HW) Chapter 31 Light Quanta

(HW) Chapter 32 The Atom & Quantum

(HW) Chapter 33 Atomic Nucleus & Radioactivity

(HW) Chapter 34 Nuclear Fission & Fusion

(HW) Chapter 35 Special Theory of Relativity

(HW) Chapter 36 General Theory of Relativity

20.) How long would the meterstick in the preceding question appear to be if it were traveling with its length perpendicular to its direction of motion?

1 m

9.) According to the simple de Broglie model, how many wavelengths are there in an electron wave in the first orbit? In the second orbit? In the nth orbit?

1, 2, n

19.) How long would a meterstick appear to be if it were traveling like a properly thrown spear at 99.5% of the speed of light?

1/10 m

2.) If you walk at 1 km/h down the aisle toward the front of a train that moves at 60 km/h, what is your speed relative to the ground?

61 km/h

16.) When thorium (atomic number 90) decays by emitting an alpha particle, what is the atomic number of the resulting nucleus?

17.) When thorium decays by emitting a beta particle, what is the atomic number of the resulting nucleus?

4.) What is a cathode ray?

A beam of electrons

Atomic Models

A complex arrangement of negatively charged electrons arranged in defined shells about a positively charged nucleus. This nucleus contains most of the atom's mass and is composed of protons and neutrons (except for common hydrogen which has only one proton)

4.) What is meant by the idea of a critical mass?

A critical mass of uranium is large enough so that neutrons ejected from one fissioning nucleus will hit another nucleus before exiting the mass.

Gravity Bends Light

A gravitational lens is a distribution of matter (such as a cluster of galaxies) between a distant light source and an observer, that is capable of bending the light from the source as the light travels towards the observer.

10.) Which of these will produce a continuous spectrum of colors?

A hot piece of wire

9.) Does light behave primarily as a wave or as a particle when it interacts with the crystals of matter in photo- graphic film?

A particle

8.) Distinguish between a rad and a rem.

A rad measures energy absorbed, whereas a rem measures biological damage done.

10.) What is a radioactive tracer?

A radioactive isotope of an element that by itself or in a molecule is used to trace biochemical pathways in plants and organisms

7. What is transmutation? What's the difference between a,b and g decay?

A transmutation entails a change in the structure of atomic nuclei and hence may be induced by a nuclear reaction (i.e. neutron capture), or occur spontaneously by radioactive decay (i.e. alpha decay, beta decay). ALPHA DECAY: a type of radioactive decay in which an atomic nucleus emits an alpha particle (helium nucleus) and thereby transforms or 'decays' into a different atomic nucleus, with a mass number that is reduced by four and an atomic number that is reduced by two. BETA DECAY: a type of radioactive decay in which a beta particle (fast energetic electron or positron) is emitted from an atomic nucleus, transforming the original nuclide to an isobar. By this process, unstable atoms obtain a more stable ratio of protons to neutrons GAMMA DECAY: type of radioactivity in which some unstable atomic nuclei dissipate excess energy by a spontaneous electromagnetic process.

1. How does an absorption spectrum differ in appearance from an emission spectrum?

ABSORPTION SPECTRUM: Absorption lines are where light has been absorbed by the atom thus you see a dip in the spectrum EMISSION SPECTRUM: Spikes in the spectra due to atoms releasing photons at those wavelengths.

Absorption Spectra

Absorption lines are where light has been absorbed by the atom thus you see a dip in the spectrum

4.) What is the same in Einstein's first postulate?

All laws of nature in all uniformly moving frames of reference

18.) What is the change in the atomic mass number for each of the reactions in the preceding two questions?

Alpha emission -4, beta emission 0

11.) How does an absorption spectrum differ in appearance from an emission spectrum?

An emission spectrum consists of bright lines against a dark background, whereas an absorption spectrum consists of dark lines against a bright rainbow background.

24.) How does the correspondence principle relate to special relativity?

At everyday low velocities, relativistic equations approach the Newtonian equations.

5. Which color light is the result of a greater energy transition: red or blue? Which better explains the photoelectric effect: the particle nature or the wave nature of electron?

Blue light has the greater energy transition. The particle nature of light better explains the photoelectric effect.

8.) Which has the higher frequency: red or blue light? Which has the greater energy per photon: red or blue light?

Blue light, blue light

5.) Compare the bending of the paths of baseballs and photons by a gravitational field.

Both follow bent paths.

CHAPTER 29 LIGHT WAVES

CHAPTER 30 LIGHT EMISSION

CHAPTER 31 LIGHT QUANTA

CHAPTER 32 THE ATOM & QUANTUM

CHAPTER 33 ATOMIC NUCLEUS & RADIOACTIVITY

CHAPTERS 34, 35, 36

7.) Which of these ejects into the atmosphere the greatest amount of dangerous radiation?

Coal-fired power plants

9.) Which of these puts the greatest amount of pollutants into the atmosphere?

Coal-fired power plants

Diffraction, Interference, Polarization

DIFFRACTION: When waves bend around small obstacles, or when waves spread out after they pass through small openings. Occurs with all waves. INTERFERENCE: a phenomenon in which two waves superpose to form a resultant wave of greater, lower, or the same amplitude. POLARIZATION: property of certain electromagnetic radiations in which the direction and magnitude of the vibrating electric field are related in a specified way.

4.) Is diffraction more pronounced through a small opening or through a large opening?

Diffraction is more pronounced through a small opening, where small is compared to a wavelength.

3. What evidence can you cite for the wave nature of particles?

Diffraction, polarization, and interference are evidence of the wave nature of light; the photoelectric effect is evidence of the particle nature of light.

3.) The energy released by nuclear fission is in accord with the celebrated equation _________.

E = mc^2

6. Be able to follow the decay paths for several steps (similar to what was done in lecture).

Each decay path will have a characteristic half-life, but some radioisotopes have more than one competing decay path. Other decay processes involve electron capture with either x-ray or electron emission afterward.

8.) Why won't a very bright beam of red light impart more energy to an ejected electron than a feeble beam of violet light?

Each electron receives energy from a single photon and violet photons have more energy than red photons.

1.) What kind of rays are X-rays?

Electromagnetic

10.) How does treating the electron as a wave rather than as a particle solve the riddle of why electron orbits are discrete?

Electron orbits can only hold an integer number of wavelengths of the electron standing wave.

Fission & Fusion

FISSION: the splitting of the nucleus of an atom into nuclei of lighter atoms, accompanied by the release of energy. FUSION: the process that powers the sun and the stars. It is the reaction in which two atoms of hydrogen combine together, or fuse, to form an atom of helium. In the process some of the mass of the hydrogen is converted into energy.

8. What's the difference between fission and fusion? Which process would release energy from carbon?

FISSION: the splitting of the nucleus of an atom into nuclei of lighter atoms, accompanied by the release of energy. FUSION: the process that powers the sun and the stars. It is the reaction in which two atoms of hydrogen combine together, or fuse, to form an atom of helium. In the process, some of the mass of the hydrogen is converted into energy. As the carbon has a lesser atomic mass than the iron, it can release the energy by the process of FUSION.

Fluorescence & Phosphorescence

2. Distinguish between fluorescence and phosphorescence. Why are some fabrics exposed to UV light so bright?

FLUORESCENCE: The emission of light by a substance that has absorbed light or other electromagnetic radiation. It is a form of luminescence. PHOSPHORESCENCE: the emission of radiation in a similar manner to fluorescence but on a longer timescale, so that emission continues after excitation ceases. When these fabrics are exposed to sunlight, the UV light excites the atoms present there that reemit white light, and so these fabrics look more bright.

3.) Which of these is electromagnetic radiation?

Gamma radiation

5.) Which has the higher frequency: X-rays or gamma rays?

Gamma rays

4.) Why aren't gamma rays deflected in a magnetic field?

Gamma rays are electromagnetic radiation and so have no charge. Electric and magnetic fields deflect charges.

5.) What were the two methods used to separate U-235 from U-238 in the Manhattan Project during World War II?

Gaseous diffusion and magnetic separation

4.) Exactly what is equivalent in the principle of equivalence?

Gravitation and acceleration

13.) In which element is the mass per nucleon greatest? Least?

Hydrogen is greatest; iron is least.

12.) Which of these elements cannot produce energy by fission or fusion?

Iron

12.) What does the wave function represent? (Symbol looks like the top of a fork)

It can be used to calculate the probability of the result of an experiment.

5.) In a neon tube, what occurs immediately after an atom is excited?

It de-excites and emits light.

12.) Time is required for light to travel along a path from one point to another. If this path is seen to be longer because of motion, what happens to the time it takes for light to travel this longer path?

It takes longer.

Light excitation & Photon

LIGHT EXCITATION: The 'shorter wavelength' light is that which is used as the 'excitation' light for fluorophores. The shorter wavelength light is absorbed by an electron of the fluorophore and as a consequence, this higher energy photon 'excites' the fluorophore. PHOTON: a type of elementary particle. It is the quantum of the electromagnetic field including electromagnetic radiation such as light and radio waves, and the force carrier for the electromagnetic force. Photons are massless, and they always move at the speed of light in vacuum.

14.) Which contains the higher percentage of neutrons: large nuclei or small nuclei?

Large nuclei (more than 50%)

5.) For an opening of a given size, is diffraction more pronounced for a longer wavelength or for a shorter wavelength?

Longer wavelengths

12.) What effect does mass have on spacetime?

Mass warps spacetime.

Mass-Energy Equivalence

Mass-energy equivalence entails that the total mass of a system may change, although the total energy and momentum remain constant; for example, the collision of an electron and a proton annihilates the mass of both particles, but creates energy in the form of photons.

11.) For what kind of gravitational field is Newton's law of gravity valid?

Newton's law is a good approximation in weak gravity fields.

21.) If you were traveling in a high-speed rocket ship, would metersticks on board appear to you to be contracted? Defend your answer.

No. The stick is in your frame of reference.

7.) What isotope is produced when U-239 emits a beta particle?

Np-239

6.) Which of these comprises the least radiation in the everyday environment?

Nuclear power plants

15.) If a certain isotope has a radioactive half-life of 10 years, how much of the isotope will remain at the end of 20 years?

One quarter

1.) Why doesn't a chain reaction normally occur in uranium mines?

Only a small fraction of natural uranium is the fissionable U-235, so most of the released neutrons do not trigger another fission.

15.) In which of the following are quantum uncertainties significant: measuring simultaneously the speed and location of a baseball, a spitball, or an electron?

Only for the electron

1.) Does the photoelectric effect support the wave theory of light? The particle theory of light?

Particle theory

1. A throbbing pulse of electromagnetic radiation is called a

Photon

Wave Model of Light

Pictures light travelling as a wave

10.) What phenomenon distinguishes longitudinal waves from transverse waves?

Polarization

2.) What two elements did Pierre and Marie Curie discover?

Polonium and radium

17.) What is the principle of complementarity?

Quantum phenomena exhibit either wavelike or particle-like properties depending on the experiment conducted.

5.) Which has the lower energy quanta: red light or blue light? Radio waves or X-rays?

Red, radio

SAMPLE MULTIPLE CHOICE QUESTIONS

SAMPLE QUESTIONS

15.) Would Schrödinger's equation be valid if applied to the solar system? Would it be useful?

Schrödinger's equation should be valid but useless.

2.) What is the principal difference between the theory of special relativity and the theory of general relativity?

Special relativity applies to frames of reference moving at constant velocity, whereas general relativity includes accelerating reference frames.

Emission Spectra

Spikes in the spectra due to atoms releasing photons at those wavelengths.

7.) What is the effect of strong gravitation on measurements of time?

Strong gravitational fields increase measured time intervals.

13.) Distinguish between monochromatic light and sunlight.

Sunlight has a wide range of frequencies and wavelengths, whereas monochromatic light has one wavelength and one frequency.

14.) Distinguish between coherent light and sunlight.

Sunlight has a wide range of frequencies, wavelengths, and phases, whereas coherent light has one wavelength, one frequency, and one phase.

Time Dilation, Twin Paradox

TIME DILATION: a slowing of time in accordance with the theory of relativity that occurs in a system in motion relative to an outside observer and that becomes apparent especially as the speed of the system approaches that of light. TWIN PARADOX: a thought experiment in special relativity involving identical twins, one of whom makes a journey into space in a high-speed rocket and returns home to find that the twin who remained on Earth has aged more.

10. What is time dilation? Use the light clock on a train to explain.

TIME DILATION: difference in the elapsed time measured by two clocks, either due to them having a velocity relative to each other, or by there being a gravitational potential difference between their locations. The light clock is a simple way of showing a basic feature of Special relativity. A clock is designed to work by bouncing a flash of light off a distant mirror and using its return to trigger another flash of light, meanwhile counting how many flashes have occurred along the way.

Transmutation & Dating

TRANSMUTATION: conversion of one chemical element into another. DATING: any method of determining the age of earth materials or objects of organic origin based on measurement of either short-lived radioactive elements or the amount of a long-lived radioactive element plus its decay product.

12.) How can astrophysicists tell whether a star is receding from or approaching Earth?

The Doppler shift of spectral lines is red for receding and blue for approaching.

11.) Why doesn't the repulsive electrical force of protons in the atomic nucleus cause the protons to fly apart?

The attractive strong nuclear force holds the nucleus together.

13.) How does the probability cloud of the electron in a hydrogen atom relate to the orbit described by Niels Bohr?

The average distance of the cloud from the nucleus is close to that of the radius of the Bohr orbit.

8.) Which runs slower: a clock at the top of the tallest skyscraper in Chicago or a clock on the shore of Lake Michigan?

The clock on the lakeshore runs slower.

9.) What do the various colors displayed in the flame of a burning log indicate?

The colors of the flames indicate the types of atoms that are emitting light in the flame.

8.) How do the distances in Reading Check Question 7 compare as seen in the frame of reference of an observer on a stationary planet?

The distance travelled by light to the back is shorter.

7.) Inside the moving compartment of Figure 35.4, light travels a certain distance to the front end and a certain distance to the back end of the compartment. How do these distances compare as seen in the frame of reference of the moving rocket?

The distances travelled by light are the same.

4. What is meant by dual nature of light? Use the double slits experiment to explain the duality of light.

The dual nature of light means that, in some experiments, light behaves as a wave. In other experiments, light behaves as a particle. In 1801, Thomas Young shined light between two adjacent slits Light travels away from a source as an electromagnetic wave. When it encounters the slits, it passes through and divides into two wave fronts.

12.) Why is a larger nucleus generally less stable than a smaller nucleus?

The electric force of repulsion between protons is a long-range force, while the attractive strong nuclear force is short-range. Repulsion wins for larger nuclei.

Photoelectric Effect

The emission of electrons from a metal when light shines on the metal

7.) What relationship between electron orbits and light emission did Bohr postulate?

The energy difference between two electron orbits would equal the energy of an emitted photon.

7.) How is the energy of a photon related to its vibrational frequency?

The energy is proportional to the frequency.

6.) How does the difference in energy between energy levels relate to the energy of the photon that is emitted by a transition between those levels?

The energy of the photon is equal to the difference in energy between the energy levels.

2.) Did Max Planck consider the energy of vibrating atoms to be quantized? The energy of light itself?

The energy of the vibrating atoms

9. What are the postulates of the special theory of relativity?

The first postulate of special relativity is the idea that the laws of physics are the same and can be stated in their simplest form in all inertial frames of reference. The second postulate of special relativity is the idea that the speed of light c is a constant, independent of the relative motion of the source.

Postulates of Special Relativity

4.) In the formula E = hf, what does f stand for?

The frequency of electromagnetic oscillation

11.) How does a hologram differ from a conventional photograph?

The hologram appears to be three dimensional. You can look around objects in a hologram.

16.) What two main obstacles prevent us from traveling today throughout the galaxy at relativistic speeds?

The large quantity of energy needed and radiation shielding

2.) Why do most alpha particles fired through a piece of gold foil emerge almost undeflected?

The massive alpha particles blast through the majority of the space in the gold that is occupied by low mass electrons.

3.) In a spaceship accelerating at g, far from Earth's gravity, how does the motion of a dropped ball compare with the motion of a ball dropped at Earth's surface?

The motions of the ball are the same.

11.) What is special about the ratio of the distance traveled by a flash of light to the time the light takes to travel this distance in a vacuum?

The ratio is always the same, the speed of light.

5.) What is constant in Einstein's second postulate?

The speed of light in a vacuum

3.) What does it mean to say an energy state is discrete?

The state has a precise energy

16.) What is the uncertainty principle with respect to momentum and position?

The uncertainty in position times the uncertainty in momentum is greater than or equal to h-bar.

21.) Which is more prevalent in the food we eat: carbon-12 or carbon-14?

There is about one carbon-14 atom for every 100 billion carbon-12 atoms.

17.) What is the universal standard of time?

There is none.

16.) Name one benefit and one drawback to breeder reactors.

They generate more fuel than they use, but they are complex to operate safely.

23.) Do the relativity equations for time, length, and momentum hold true for everyday speeds? Explain.

They hold true but the differences they predict are hard to measure.

9.) What shifts in the gravitational red shift?

Time

13.) What do we call the "stretching out" of time?

Time dilation

14.) If a flashing light source moves toward you fast enough so that the time interval between flashes is half as long, how long will the time interval between flashes be if the source is moving away from you at the same speed?

Twice as long

2.) Which of these typically undergoes a chain reaction?

U-235

8.) Name two isotopes that can undergo fission when they absorb a neutron.

U-235, Pu-239

17.) What element reacts in a breeder reactor to breed nuclear fuel?

U-238

6.) What isotope is produced when U-238 absorbs a neutron?

U-239

3. Which of the following photons has the greatest energy?

Ultraviolet

7.) Which are more successful in dislodging electrons from a metal surface: photons of violet light or photons of red light? Why?

Violet light is more successful because the higher energy of a violet photon interacts with a single electron and gives it enough energy to escape the metal.

2.) Electrons made to vibrate to and fro at a few hundred thousand hertz emit radio waves. What class of waves is emitted from electron vibrations of a few million billion hertz?

Visible light

10.) Does light travel from one place to another in a wavelike or a particle-like way?

Wavelike

10.) Under what condition will you and a friend share the same realm of spacetime?

We experience the same spacetime when we are in the same frame of reference with zero velocity relative to each other.

6.) Why must the Sun be eclipsed to measure the deflection of starlight passing near the Sun?

Without an eclipse, the Sun's glare makes it impossible to see stars near the Sun.

9.) Is the human body radioactive? Explain.

Yes. The potassium in our bodies has a radioactive isotope that is the main internal source of radiation for a human body.

Double-Slit

a demonstration that light and matter can display characteristics of both classically defined waves and particles; moreover, it displays the fundamentally probabilistic nature of quantum mechanical phenomena.

8.) The electric vectors that make up polarized light are _________.

aligned

2. The energy of a photon is related to

all of these (the energy given to the atom that emits it; the energy level difference though which it falls; its frequency)

15.) Tritium, a choice fuel for fusion, is _________.

almost completely absent in nature

14.) In the process of nuclear fusion, elements _________.

combine

9.) The unifying factor that unites different realms of spacetime is the _________.

constant speed of light

6. When Rutherford directed a stream of alpha particles at a gold foil, most particles

continued through.

Quantum Mechanics

describes how the Universe works at the level smaller than atoms.

3.) Any bending of light that is not reflected or refracted is due to _________.

diffraction

5.) The spectra of atoms reveals their _________.

electron structure and atomic identity

1.) The emission of light has most to do with the behavior of _________.

electrons

9.) Light reflecting from a horizontal surface is likely to be polarized _________.

horizontally

Principle of Equivalence

in any small region of space-time, the effects of a gravitational field are indistinguishable from those of an appropriate acceleration of the frame of reference.

7.) A diffraction grating separates light into its component colors by the process of _________.

interference

8.) Bohr stated that electrons in an atom can undergo _________.

interference

2.) Huygens' principle features wavefronts that are composed of _________.

overlapping waves

4. The photoelectric effect best demonstrates the

particle nature of light.

11.) In the celebrated equation E = mc^2, the c^2 is the _________.

proportionality constant of energy and mass

6.) A central feature of Bohr's model of the atom is _________.

quantum jumps of energy

1.) The great discovery of Rutherford was _________.

the atomic nucleus

Uncertainty Principle

the idea put forth by Werner Heisenberg in 1927 that the behavior of subatomic particles is uncertain, suggesting that all of the physical laws governing the universe are based on uncertainty

Length Contraction

the phenomenon that a moving object's length is measured to be shorter than its proper length, which is the length as measured in the object's own rest frame. Length contraction is only in the direction in which the body is travelling.

Half-Life

the time required for a quantity to reduce to half of its initial value. The term is commonly used in nuclear physics to describe how quickly unstable atoms undergo, or how long stable atoms survive, radioactive decay.

Physics Study Guide Ch. 29-36 + Homework

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