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Physics Middle School

Food borne pathogens are harmful to the human body in any amount

2 months ago

Solution 1

Guest #2509

2 months ago

Not true. For all diseases caused by pathogens (even viruses), there is a minimum infectious dose needed to cause disease.

It does vary between different pathogens & between the condition of the host (immunocompromised vs. healthy), but if the minimum infectious dose is not met- then the body is typically able to snuff out the intruders before they can do any real damage.

Hope that helps!

📚 Related Questions

Question

According to the electromagnetic spectrum, Gamma rays have the slowest wave length. Therefore, Gamma rays have _______frequency. A). a random B). the lowest C). the highest D). an undetermined

Solution 1

According to the electromagnetic spectrum, gamma rays have the slowest wave length. therefore, gamma rays have the highest frequency.

Solution 2

Answer:

A. the highest

Question

Why are the phases of the Moon so predictable that they can be published on calendars that are printed at least a year ahead of time?

Solution 1

With my best educated guess it's just like knowing when the triangle in a shape pattern comes up again.
They know what the moon looks like if it was night time and so they say "Hey, since we got this moon phase right now then this other moon phase is going to be tomorrow!" and so they keep going.
With the knowing when the next blue moon or blood moon will come they look at other times it has happened and connect the dots telling them "Every this amount of days the blue moon will come." Again this is just my educated guess so I could be a correct but it be more science to it.
Hope at least I gave you a good idea.

Question

Measuring the Orbital Speeds of Planets Introduction A Boeing 747 can fly 624 miles per hour. That’s pretty fast! Right now, Earth and other objects in the solar system are orbiting the Sun, but how fast are these objects moving? In this assignment, you will calculate the orbital speeds of objects in our solar system. Part A: Planetary Periods In the 1600s, Johannes Kepler discovered three laws that govern the motion of objects around the sun. Kepler’s first law explains that objects travel in an elliptical, or oval-shaped, path around the sun. Kepler’s second law explains that an object travels faster in its orbit when it is closer to the Sun and slower in its orbit when it is farther away. In this activity, you will investigate Kepler’s third law: the relationship between an object’s distance from the sun and the time it takes the object to complete an orbit around the sun. Access the Gizmo from within today's lesson. The exploration guide found within this simulation will help you work through the Gizmo. Click on the Lesson Materials link, which appears on the top left corner of the screen once you enter the simulation, to access the student exploration sheet. Use it as you work through Activity C and answer all parts. Part B: Calculating Orbital Speed Every object moves at a different average speed in its orbit around the Sun. In this activity, you will use data collected from Part A to calculate the average orbital speeds of each planet and of Pluto. 1. Recall that the path an object takes around the Sun is an ellipse, and not a circle. However, to approximate the circumference, or length, of each orbit, you will treat the orbits as circles. Go back to your notes in your student exploration sheet from Part A. Using the mean orbital radius (R) that you recorded, calculate the circumference of each planet’s orbit and record it in the table below. Use the following formula to calculate the circumference: Circumference 2 = π r 2. Using the periods you recorded in your student exploration sheet and the circumference of orbit that you just calculated, calculate the average orbital speed of each planet and record it in the table below. Use the following formula to calculate speed: Distance Circumference Average Orbital Speed Time Period = = The units of your answer will be in AU/year. 3. To give you a better perspective of how fast these orbital speeds really are, convert the orbital speeds you just calculated from AU/year to miles/hour. 1 AU/year = 10,604 miles/hour. Record your answers in the table below. Table Object Mean orbital radius (AU) (copy from #6 in part A) Circumference of Orbit (AU) Period (Earth Years) (copy from #6 in part A) Orbital Speed (AU/year) Orbital Speed (miles/hour) Mercury Venus Earth Mars Jupiter Saturn Uranus Neptune Pluto Drawing Conclusions 4. Which planet takes the longest amount of time to travel once around its orbit? Which planet takes the shortest amount of time? 5. How does an increase in orbital radius affect average orbital speed? Extension perihelion In astronomy, the term refers to the point in the orbit of an asteroid, comet, or planet at which it is closest to the sun. Aphelion refers to the point at which the object is furthest away from the sun. Research facts about the dwarf planet Ceres. Calculate the average orbital speed of Ceres in miles/hour when it is closest to the sun and when it is farthest away.

Solution 1

Kepler's third law allows finding the answers for the orbital speed of the planets are:

The speed decreases as we move away from the Sun, the values are in the third column of the table.

The fastest planet is Mercury and the slowest planet is Pluto.

Kepler measured and analyzed the astronomical data of him and his tutor Brake, finding mathematical relationships that describe the movement of the planet, they are called Kepler's laws

1. The orbits are ellipses

2. A vector from the sun to the planet travels equal areas in equal times

3. A relationship between the period and the semi-major axis of the orbit.

Kepler's third law is an application of Newton's second law to the motion of the planets around the sun.

Newton's second law establishes a relationship between force and the product of mass and acceleration of the object; in this case the force is the gravitational attractive force

F = m a

F = $G \frac{M m}{r^2}$

Wher M y m are sum and planet mass, r is the distance ang G constnate universal gravitation

They indicate that we consider the orbits as circular, in this case the acceleration is centripetal

a = $\frac{v^2}{r}$

Let's substitute

$G \frac{M m}{r^2} = m \frac{ v^2}{r}$

$v = \sqrt{ \frac{GM }{r} }$ (1)

The modulus of velocity (speed) is constant so we can use the uniform motion ratio

v = $\frac{\Delta x}{t}$

For a complete orbit, the distance traveled is the length of the circle and the time is called the period.

Δx = 2π r

we substitute

$\frac{G M}{r} = \frac{4 \pi^2 r^2 }{T^2}$

T² = ( $\frac{4\pi ^2 }{GM}$ ) r³

They ask to calculate the orbital velocity we can use the relation 1

v = $\frac{\sqrt{GM }}{ \sqrt{r} }$

Let's find the value of the constant

$\sqrt{GM}$ = $\sqrt{6.67 \ 10^{-11} \ 1.991 \ 10^{30}}$

$\sqrt{GM} = 1.15 \ 10^{10}$

In the table we have the tabulated values for the radii of the orbits of the planets

planet radius orbit (m) velocity (m/s)

Mercury 5.79 10¹⁰ 4.779 10⁴

Venus 1.08 10¹¹ 3.499 10⁴

Land 1,496 10¹¹ 2,973 10⁴

Mars 2.28 10¹¹ 2.408 10⁴

Jupiter 7.78 10¹¹ 1.304 10⁴

Saturn 1.43 10¹² 9.62 10³

Uranus 2.87 10¹² 6.79 10³

Neptune 4.50 10¹² 5.42 10³

Pluto 5.91 10¹² 4.73 10³

We calculate the speed of some as an example and the others are in the third column of the table

Mercury

v = $\frac{1.15 \ 10^{10}}{\sqrt{5.79 \ 10^{10}} }$

v = 4.779 10⁴ m / s

Venus

v = $\frac{1.15 \ 10^{10}}{\sqrt{1.08 \ 10^{11}} }$

v = 3,499 10⁴ m / s

They ask to know the planet that has maximum and minimum orbital speed.

After reviewing the calculations, and observed the table, Mercury has the highest speed and Pluto is the one with the lowest orbital speed.

When examining the expression the velocity is inversely proportional to the square root of the radius of the orbit

The radius of the orbit of Ceres is r = 2.766 ua ( $\frac{1.49 \ 10^{11} m}{1 ua}$ ) = 4.11 10¹¹ m

the orbital velocity of Ceres is

v = $\frac{1.15 \ 10^{10}}{\sqrt{4.11 \ 10^{11}} }$

v = 1.79 10⁴ m / s

those that correspond to a speed between Mars and Jupiter

In conclusion using Kepler's third law we can find the answers for the orbital speed of the planets are:

The speed decreases as we move away from the Sun, the values are in the third column of the table.

The fastest planet is Mercury and the slowest planet is Pluto.

Learn more here: brainly.com/question/9622816

Solution 2

The branch of science that deals with celestial objects, space, and the physical universe as a whole.

Question

One complete revolution of Earth around the sun takes about a. one rotation. b. one season. c. one year. d. one eclipse.

Solution 1

One complete revolution of Earth around the sun takes

c. one year

Solution 2

One complete revolution of Earth around the sun takes about one year (C).

Question

How does the density of a medium affectthe speed of a wave traveling through it

Solution 1

The denser the medium, the harder the sound struggles to travel through. The medium will determine how effectively the sound will travel, for example, large bodies of water has barely any sound for its density.

Question

Which statement about the free enterprise system is true? It allows the citizen to own government property. It exempts the citizen from taxes if that person serves the government. It allows the citizen to share political power with the rest of the population. It allows the citizen to own and operate a private business for profit. It allows the citizen to be part of a one-class system under state control.

Solution 1

It allows the citizen to own and operate a private business for profit.

Question

Which statement about the free enterprise system is true?

Solution 1

The free enterprise system allows the citizen to own and operate a private business for profit.

The basic principles of a free enterprise system were laid out by Scottish philosopher Adam Smith in an influential book published in 1776: An Inquiry into the Nature and Causes of the Wealth of Nations. The Nobel-prize winning 20th century economist Milton Friedman said of Adam Smith, "The key insight of Adam Smith's Wealth of Nations is misleadingly simple: If an exchange between two parties is voluntary, it will not take place unless both believe they will benefit from it." Smith argued for such voluntary exchanges within a free market system. He labeled the government-manipulated economic system that was prevailing in his day as "mercantilism," a system in which governments specifically authorized some merchants as the official agents of commerce (rather than endorsing free enterprise). The mercantilist system also viewed wealth as though there were a fixed amount of it available in the world, represented by precious metals such as gold and silver, and that nations were in competition over who got more of that fixed amount of world wealth. Smith saw that wealth was something that could be created and increased through voluntary exchange and free enterprise. Smith's ideas formed the basis for what we have come to know as capitalism.

Solution 2

The citizen to own and operate a private business for profit.

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