Answer:
The age of the earliest known human-like footprints is approximately 3000000 years.
Explanation:
Decay of isotopes is represented by the following ordinary differential equation:
[tex]\frac{dm}{dt} = -\frac{m}{\tau}[/tex] (Eq. 1)
Where:
[tex]\frac{dm}{dt}[/tex] - First derivative of mass with respect to time, measured in miligrams per year.
[tex]m[/tex] - Current mass of the isotope, measured in miligrams.
[tex]\tau[/tex] - Time constant, measured in years.
Now we proceed to obtain the solution of the differential equation:
[tex]\int\limits {\frac{dm}{m} } = -\frac{1}{\tau}\int dt[/tex]
[tex]\ln m = -\frac{t}{\tau}+C[/tex]
[tex]m(t) = e^{-\frac{t}{\tau}+C }[/tex]
[tex]m(t) = m_{o}\cdot e^{-\frac{t}{\tau} }[/tex] (Eq. 2)
Where:
[tex]m_{o}[/tex] - Initial mass of the isotope, measured in miligrams.
[tex]t[/tex] - Time, measured in years.
[tex]\tau[/tex] - Time constant, measured in years.
We proceed to clear time within the formula presented above:
[tex]\ln \frac{m(t)}{m_{o}} = -\frac{t}{\tau}[/tex]
[tex]t = -\tau \cdot \ln \frac{m(t)}{m_{o}}[/tex]
In addition, time constant can be found as a function of half-life:
[tex]\tau = \frac{t_{1/2}}{\ln 2}[/tex] (Eq. 3)
If we know that [tex]t_{1/2} = 500000\,yr[/tex], [tex]m_{o} = 8\,mg[/tex] and [tex]m(t) = 0.125\,mg[/tex], the age of the earliest known human-like footprints is:
[tex]\tau = \frac{500000\,yr}{\ln 2}[/tex]
[tex]\tau \approx 721347.520\,yr[/tex]
[tex]t = -(721347.520\,yr)\cdot \ln \left(\frac{0.125\,mg}{8\,mg} \right)[/tex]
[tex]t \approx 3000000\,yr[/tex]
The age of the earliest known human-like footprints is approximately 3000000 years.
Maria wants to determine which type of disinfectant kills the most bacteria.
Which of the following is the best way for Maria to determine this?
A.
Interview ten different people to determine which type of disinfectant they prefer.
B.
Put the same amount and species of bacteria on ten identical plates, and add ten different kinds of disinfectant to each plate.
C.
Ask ten different companies that make disinfectants which type is best.
D.
Put the same amount and species of bacteria on ten identical plates, and add a different disinfectant to each plate.
A I think thats what I would put
How long does it take for the water to start boiling? At what temperature does the water boil?
Answer:
At sea level, or at zero feet in altitude, the boiling point of water is at 212 °F (100 °C). Once the water has reached this boiling point, the US Center for Disease Control recommends keeping it at a rolling boil for about a minute to make sure it is purified.
Answer:
Water boils at 212 degrees fahrenheit or 100 degree celcius
Explanation:
its true
sexual reproduction helps to increase
a. the number of offspring
b. genetic variation
c. genetic mutations
Answer:
a. the number of offspring would be ur answer pls make me brainliest
HELP MEEEEEEEEEEEE
Winds and ocean breezes occur due to _____________.
A. None of these
B. Conduction currents
C. Boiling
D. Convection currents
Answer:
B
Explanation:
it flows by the conduction currents
fghgfgfgfftftftft ttcc
Answer:
fghgfgfgftftftftftft ttcc
tehee
Explanation:
N= 0.785 mol N2
P= 1.5 atm
T= 301 K
V=?
FAST PLZ
Answer:
V=13.031L
Explanation:
Use the equation PV=nRT. n is moles, R is 8.31, T is temp in (K), and Pressure in KPa
If anyone have the answers to this plz tell me
Explanation:
hey can I please get the passage so that I can help you
What type of mixture is separated by effusion and condensation?
a.
Liquid
c.
Gaseous
b.
Solid
d.
Combination of liquid and solid
Answer:
c is the answer then check it out
A worker is melting samples of various metals. Which sample will require the most heating to melt?
(check upload for chart)
A.
1 kg of aluminum
B.
2 kg of nickel
C.
3 kg of silver
D.
5 kg of tin
[Ne] 3s^ 2 3p^ 4 can someone tell me the element
Answer:
Sulpher
Explanation:
For this type of questions; calculate the total number of electrons so that you can identify the element from the periodic table.
Neon has 10 electrons. and from 3s^2 and 3p^4 there are 6 electrons.
So the total number of electrons is 16.
The element is Sulpher from group 6 of the periodic table
A sample of matter is made up of three different atoms that are chemically combined. What
type of matter is it? How do you know?
Answer:
liquid
Explanation:
a molecule consists of different atoms chemically combined. A molecule is also a liquid. Molecules make up ice cubes, which are also small water particles which arr yet again liquid.
If an atom has 3 protons, what is its atomic number?
Answer:
Atomic Number = 3.
Explanation:
The number of protons determines the atomic number. Basically the number of protons is the exact same as the atomic number.
Protons 3 = Atomic number 3
Quartzite is a coarse-grained rock derived from sandstone.
Which type of rock is quartzite?
metamorphic
extrusive
sedimentary
igneous
Answer:
granoblastic metamorphic rock
Explanation:
The formula for density (D) is D = m/v, where m is mass and v is volume. What is the mass in grams (g) of a 45.0 cubic centimeters (cm³) block of silicon if the density of silicon is 2.336 grams per cubic centimeters (g/cm³)
A. the mass is 0.0519 g.
B. the mass is 19.3 g.
C. the mass is 45.0 g.
D. the mass is 105 g.
Answer:
The answer is D. The mass is 105g.
Which two systems does the nervous system work with to direct behavior
and movement? *
O digestive and respiratory
muscular and skeletal
O excretory and digestive
circulatory and digestive
To solve this we must be knowing each and every concept related to nervous system. Therefore, "the muscular and skeletal system " is the correct option.
What is nervous system?The nervous system serves as a link between the environment and the organism's interactions. The nervous system coordinates actions or sensory information by sending and receiving signals to and from various sections of the body.
The peripheral and central systems are the two sections of the nervous system. They aid in the appropriate step-by-step coordination of the many physical reactions and communications from the parts of the body to the brain and back. The muscular and skeletal system, the nervous system work with to direct behavior and movement.
Therefore, "the muscular and skeletal system " is the correct option.
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3. How do you observe stuff?
Answer:
by looking at the and researching for super long
Explanation:
Where are hormones produced in animals, and how are they transported throughout the body?
A. Animal hormones are produced in endocrine glands and travel through the blood.
B. Animal hormones are produced in lymph nodes and travel through the lymphatic system.
C. Animal hormones are produced inside the bones and travel through the nervous system.
D. Animal hormones are produced in sweat glands and travel through the skin.
Answer:
Vertebrate Endocrine Glands and Hormones
Unlike plant hormones, animal hormones are often (though not always) produced in specialized hormone-synthesizing glands (shown below). The hormones are then secreted from the glands into the blood stream, where they are transported throughout the body.
Pls fill in the blank
Because it can either lose or share electrons when it combines with has some of the properties of metals and
other elements, each has some of the properties of nonmetals.
A. Metalloids
B. Sodium
C. Gold
A. Metalloids
They can either lose an electron or share an electron when it combines with other elements. They have some properties of metals and some properties of non-metals.
What is the pi of 80,000 and 400000
Answer:
london I'm not dead -yet-
Explanation:
thank u for being there for me when no one else was
btw she visited me last night "I made sure to punch her in da nose but my fist hit the wall instead of her face so yea funnn" good luck in this life
Hydrogen is in column 1 of the periodic table. What information does this give us? (2 points)
There is one other element that hydrogen will bond with.
There is one neutron in the nucleus.
The mass of the atom is one.
There is one electron in the outer energy level.
Answer:
the last one
Explanation:
ydyeusueueueueudhs
Because hydrogen forms compounds with oxidation numbers of both +1 and -1, many periodic tables include this element in both Group IA (with Li, Na, K, Rb, Cs, and Fr) and Group VIIA (with F, Cl, Br, I, and At).
There are many reasons for including hydrogen among the elements in Group IA. It forms compounds (such as HCl and HNO3) that are analogs of alkali metal compounds (such as NaCl and KNO3). Under conditions of very high pressure, it has the properties of a metal. (It has been argued, for example, that any hydrogen present at the center of the planet Jupiter is likely to be a metallic solid.) Finally, hydrogen combines with a handful of metals, such as scandium, titanium, chromium, nickel, or palladium, to form materials that behave as if they were alloys of two metals.
There are equally valid arguments for placing hydrogen in Group VIIA. It forms compounds (such as NaH and CaH2) that are analogs of halogen compounds (such as NaF and CaCl2). It also combines with other nonmetals to form covalent compounds (such as H2O, CH4, and NH3), the way a nonmetal should. Finally, the element is a gas at room temperature and atmospheric pressure, like other nonmetals (such as O2 and N2).
It is difficult to decide where hydrogen belongs in the periodic table because of the physical properties of the element. The first ionization energy of hydrogen (1312 kJ/mol), for example, is roughly halfway between the elements with the largest (2372 kJ/mol) and smallest (376 kJ/mol) ionization energies. Hydrogen also has an electronegativity (EN = 2.20) halfway between the extremes of the most electronegative (EN = 3.98) and least electronegative (EN = 0.7) elements. On the basis of electronegativity, it is tempting to classify hydrogen as a semimeta
Which type of fault is under compression? A. Normal. B. Thrust. C. Transform. D. Strike-slip
Answer:
The answer is Thrust
Is calcium chloride reactive?
Answer:
Yes it is
Explanation:
calcium chloride releases heat in an exothermic reaction.
yes.
hope is helps! :)
3.Zinc has an atomic number of 30 and a mass number of 65, how many neutrons does it have?
30
65
35
95
Answer:
35
Explanation:
Given parameters:
Atomic number of zinc = 30
Mass number of zinc = 65
Unknown
Number of neutrons = ?
Solution:
The mass number of an atom is the sum of its protons and neutrons;
Mass number = Protons + neutrons
Atomic number is the number of protons in an atom;
Atomic number = Protons
So;
Mass number = Atomic number + Neutrons
Neutrons = Mass number - Atomic number
Neutrons = 65 - 30 = 35
The number of neutrons in the atom is 35
ANSWER FAST PLEASE!!
Which is a true statement about a zero net force?
A zero net force causes a change to an object’s direction.
B.zero net force causes a change to an object’s speed.
C.A zero net force causes a change to an object’s acceleration.
D.A zero net force causes no change in an objects motion.
Answer:
D)a zero net force causes no change in an objects motion.
A zero net force causes no change in an object's motion. This statement is true about zero net force. Therefore, option D is correct.
What is zero net force ?An item that is originally at rest and has no net forces operating on it will stay at rest. If it is going, it will keep moving straight forward at a consistent speed. Forces are "pushes" or "pulls" on the object, and they are vector numbers, just like acceleration and velocity.
A automobile travelling at 50 mph on a highway continually has a net force of zero even though it is moving, since there is no acceleration and the speed is constant.
The total net force acting on an object as it moves at a steady speed is always zero. If you apply force, friction or another force (or several forces) will balance it out.
Thus, option D is correct.
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During a scientific investigation, which step will a scientist perform first?
Answer:
you need to have a question or a problem first
what is the meaning of mass
Answer:
Mass is both a property of a physical body and a measure of its resistance to acceleration when a net force is applied.
Explanation:
Which of the following best describes a function of the nervous system as
discussed in class?
to store urine
O to move limbs
to receive stimuli from inside and outside the body
to take in oxygen and transport it to the cells
Answer: The answer is to receive stimuli from inside and outside the body.
Explanation:
Apps
What do you already know about mass, weight, and gravity?
Answer:
they are the three states of matter
Can yall plz help me!!!!!!!!!!!!
Define the terms below:
● Axis:
● Rotation:
● Revolution:
● Elliptical Orbit:
Answer:
Axis
Anatomy
In anatomy, the second cervical vertebra of the spine is named the axis or epistropheus. By the atlanto-axial joint, it forms the pivot upon which the first cervical vertebra, which carries the head, rotates.
Rotation
A rotation is a circular movement of an object around a center of rotation. A three-dimensional object can always be rotated about an infinite number of imaginary lines called rotation axis. If the axis passes through the body's center of mass, the body is said to rotate upon itself, or spin.
Revolution
In political science, a revolution is a fundamental and relatively sudden change in political power and political organization which occurs when the population revolts against the government, typically due to perceived oppression or political incompetence.
Elliptic orbit
In astrodynamics or celestial mechanics, an elliptic orbit or elliptical orbit is a Kepler orbit with an eccentricity of less than 1; this includes the special case of a circular orbit, with eccentricity equal to 0. In a stricter sense, it is a Kepler orbit with the eccentricity greater than 0 and less than 1.
:) gimme a crown plz
3.
The dimensions of a cuboid are in the ratio of 1:2:3 and its total surface area is
88m square. Find
the dimensions.
Answer:
The length of the cuboid =x=2m, breadth =2x=4m, height =3x=6m
Explanation:
Let the length of the cuboid =x, breadth =2x, height =3x
Total surface area of a cuboid =2(l×b+b×h+l×h)
Given, total surface area of the cuboid =88m^2
2( x*2x + 2x*3x + x*3x )=88m
22x^2 =88
x=2
Hence, the length of the cuboid =x=2m, breadth =2x=4m, height =3x=6m