Answer:
In 1869 Russian chemist Dimitri Mendeleev started the development of the periodic table, arranging chemical elements by atomic mass. He predicted the discovery of other elements, and left spaces open in his periodic table for them.
Explanation:
Answer: Mendeleev first published a table of elements arranged according to increasing atomic masses. He noticed that some elements near each other had differing properties, but elements in vertical columns had similar properties. Moseley then rearranged the table according to atomic numbers and this eliminated the discrepancies found in Mendeleev’s attempt. Today’s version of the periodic table displays elements in order based on their atomic number; the atomic number indicates the number of protons within the atoms of a particular element. Rows are called periods and columns are called groups. Elements in the same group have similar properties. Elements are grouped into nine categories: noble gases, halogens, nonmetals, alkali metals, alkaline earth metals, transition metals, other metals, metalloids, and rare earth elements.
Which of the following is true?
A
The Atlantic, Pacific, Indian, Arctic, and Southern Oceans are completely separate
from each other.
B
The ocean covers about half of the Earth's surface.
с
Scientists have studied most of the ocean, but a tiny bit remains unexplored.
D
Scientists know more about the moon than they do the ocean.
Answer:
options B,C,D are true
Explanation:
Galaxy B moves away from galaxy A at 0.577 times the speed of light. Galaxy C moves away from galaxy B in the same direction at 0.731 times the speed of light. How fast does galaxy C recede from galaxy A?
Answer:
The value is [tex]p = 0.7556 c[/tex]
Explanation:
From the question we are told that
The speed at which galaxy B moves away from galaxy A is [tex]v = 0.577c[/tex]
Here c is the speed of light with value [tex]c = 3.0 *10^{8} \ m/s[/tex]
The speed at which galaxy C moves away from galaxy B is [tex]u = 0.731 c[/tex]
Generally from the equation of relative speed we have that
[tex]u = \frac{p - v}{ 1 - \frac{ p * v}{c^2} }[/tex]
Here p is the velocity at which galaxy C recede from galaxy A so
[tex]0.731c = \frac{p - 0.577c }{ 1 - \frac{ p * 0.577c}{c^2} }[/tex]
=> [tex]0.731c [1 - \frac{ p * 0.577}{c}] = p - 0.577c[/tex]
=> [tex]0.731c - 0.4218 p = p - 0.577c[/tex]
=> [tex]0.731c + 0.577c = p + 0.4218 p[/tex]
=> [tex]1.308 c = 1.731 p[/tex]
=> [tex]p = 0.7556 c[/tex]
Thorium^+2
Chemical symbol:
Atomic Number:
Mass: 232
# of protons
# of neutrons
Group #
Period #
Answer:
chemical symbol: Th
atomic number:90
protrons :90
neutrons:142
group#:4
period#: 9
Explanation:
you take the atomic weight (232.038)and subtract the atomic number to get (90) which is your neutrons
A certain heat engine does 30.2 kJ of work and dissipates 9.14 kJ of waste heat in a cyclical process.
A) What was the heat input to this engine?
B) What was its efficiency?
Answer:
a) [tex]H_{in}=39.34 kJ[/tex]
b) Efficiency=76.77%
Explanation:
a)
In order to solve this problem, we can use the following formula:
[tex]H_{in}=H_{out}+W[/tex]
the problem provides us with all the necessary information so we can directly use the formula:
[tex]H_{in}=9.14kJ+30.2kJ[/tex]
[tex]H_{in}=39.34 kJ[/tex]
b) In order to find the efficiency, we can use the following formula:
[tex]Efficiency=\frac{W}{H_{in}}*100\%[/tex]
so we get:
[tex]Efficiency=\frac{30.2kJ}{39.34kJ}*100\%[/tex]
Efficiency=76.77%
In order to prevent injury in a car crash, it is recommended that you _______.
A) Increase the time of the collision.
B) Increase the change in momentum of the collision.
C) Increase the force in the collision.
D) Increase the initial velocity of the collision.
Increase of momentum of the collision will have the car in a unsettling position, creating an unsettling spot for it. Moreover increasing this would most likely take worse effect, it is better than increasing the time, which will only create the car faster. Let me show you what I mean...
A) Creates the car go faster, creating an even worse tragedy. B) save this for later...C) Increasing force will only result in worse damage.And finally, D) Increasing the velocity is basically increasing speed, once again, making things worse.So overall in this piece, the answer may very well end up being B. I sincerely hope this helped you by whatever means possible. It's logic that helps in real life situations, so take this as a little lesson- I guess :3name the force that help us to walk
Describe the motion of an object as it accelerates. IN YOUR OWN WORD!! ASAP
Answer:
The aceleration of an object is in the direction of the net force. If you push or pull an object in a particular direction, it accelerates in that direction. The aceleration has a magnitude directly proportional to the magnitude of the net force.
Explanation:
Hope this helps Plz mark brainliest
convert 100 Newton into dyne
Answer:10000000
Explanation:
Which objects cannot be observed in detail without a microscope?
Answer:
partecls
Explanation:
because they are to small to see with plain eyes
Compute the specific heat capacity at constant volume of nitrogen (N2) gas. The molar mass of N2 is 28.0 g/mol.
Answer:
724.3J/Kg.K
Explanation:
CHECK THE COMPLETE QUESTION BELOW
Compute the specific heat capacity at constant volume of nitrogen (N2) gas.and compare with specific heat of liquid water. The molar mass of N2 is 28.0 g/mol.
The specific heat capacity can be computed by using expression below
c= CV/M
Where c= specific heat capacity
M= molar mass
CV= molar hear capacity
Nitrogen is a diatomic element, the Cv can be related to gas constant with 5/2R
Where R= 8.314J/mol.k
Molar mass= 28 ×10^-3Kg/mol
If we substitute to the expression, we have
c= (5R/2)/(M)
=5R/2 × 1/M
=(5×8.314) /(2×28 ×10^-3)
=724.3J/Kg.K
Hence, the specific heat capacity at constant volume of nitrogen (N2) gas is
724.3J/Kg.K
The specific heat of liquid water is about 4182 J/(K kg) which is among substance with high specific heat, therefore specific heat of Nitrogen gas is 724.3J/Kg.K which is low compare to that of liquid water.
one newton equals 0.225
A mover slides a refrigerator weighing 650 N at a constant velocity across the floor a distance of 8.1 m. The force of friction between the refrigerator and the floor is 230 N. How much work has been performed by the mover on the refrigerator?
Given :
A mover slides a refrigerator weighing 650 N at a constant velocity across the floor a distance of 8.1 m.
The force of friction between the refrigerator and the floor is 230 N.
To Find :
How much work has been performed by the mover on the refrigerator.
Solution :
Since, refrigerator is moving with constant velocity.
So, force applied by the mover is also 230 N ( equal to force of friction ).
Now, work done in order to move the refrigerator is :
[tex]W = Force\times distance\\\\W = 230 \times 8.1\ N\ m\\\\W = 1863\ N\ m[/tex]
Hence, this is the required solution.
A sled is pulled with a force of 540 N at an angle of 40° with the horizontal. What are the horizontal and vertical components of this force?
Answer:
Fx = 467.65N
Fy = 270N
Explanation:
Given
Force = 540N
angle of inclination = 40 degree
Horizontal component Fx = Fcos 30
Fx = 540cos30
Fx = 540(0.8660)
Fx = 467.65N
Hence the horizontal component is 467.65N
Vertical component Fy = Fsin 30
Fy = 540sin30
Fy = 540(0.5)
Fy = 270N
Hence the vertical component is 270N
What is the acceleration of the the object during the first 4 seconds?
Answer:
Velocity (m/s) over time (s) graph
Velocity (m/s) over time (s) graph
We could write out our average acceleration as:
a = Δv/ Δta=Δv/Δta, equals, Δ, v, slash, Δ, t
a = (15 m/s - 0 m/s) / 0.2 seconds
a = 15 m/s / 0.2 seconds
a = 75 m/s / second
Explanation:
What this formula is telling us is that if we know the acceleration of an object, and the ... we can plug in our acceleration of 12.5 m/s2 for a, and 4 seconds for t.
Velocity (m/s) over time (s) graph
Velocity (m/s) over time (s) graph
We could write out our average acceleration as:
a = Δv/ Δta=Δv/Δta, equals, Δ, v, slash, Δ, t
a = (15 m/s - 0 m/s) / 0.2 seconds
a = 15 m/s / 0.2 seconds
a = 75 m/s / second
A statement of the second law of thermodynamics is that:__________.
a) spontaneous reactions are always exothermic.
b) energy is conserved in a chemical reaction that has a decrease in entropy.
c) spontaneous reactions are always endothermic.
d) in a spontaneous process, the entropy of the universe increases.
Answer:
in a spontaneous process, the entropy of the universe increases.
Explanation:
Entropy is a measure of of the degree of randomness or disorderliness in a system.
The second law of thermodynamics can be stated as follows; "in any spontaneous process, the entropy of the universe increases."
The universe here refers to the system's disorder and the disorder of the surroundings. Therefore, a spontaneous process can occur, in which the entropy of the system decreases, only if the entropy increases in the surroundings.
For instance, when ice freezes, the entropy of liquid water decreases, that is, the entropy of the system decreases. However, heat is given off to the surroundings and the entropy of the surroundings increases. This is an obvious expression of this law.
What is the distance between a 900 kg compact car and a 1600 kg pickup truck if the gravitational force between them is about 0.0001 N?
Answer:
The distance is 0.96m
Explanation:
Given
m1= 900kg
m2= 1600kg
Force F= 0.0001nN
G=6.67430*10^-11 Nm^2/kg^2
Required
The distance r
Step two:
the formula for the force is given as
F = Gm1m2/r2
make r subject of the formula
[tex]r= \sqrt{\frac{Gm1m2}{F} }[/tex]
[tex]r= \sqrt{\frac{6.67430*10^-11*900*1600}{0.0001} }\\\\r= 0.00009610992/0.0001`}\\\\r= 0.96m[/tex]
Answer:
The distance is 0.96m
Explanation:
Given
m1= 900kg
m2= 1600kg
Force F= 0.0001nN
G=6.67430*10^-11 Nm^2/kg^2
Required:
The distance r
Step two:
the formula for the force is given as
F = Gm1m2/r2
make r subject of the formula
[tex]r= \sqrt{\frac{Gm1m2}{F} }[/tex]
[tex]r= \sqrt{\frac{6.67430*10^-11*900*1600}{0.0001} }\\\\r= 0.00009610992/0.0001`}\\\\r= 0.96m[/tex]
Answer:
The distance between the compact car and pickup truck is 0.96048 m
Explanation:
The gravitational force is directly proportional to the product of the masses of the interacting object, it is also inversely proportional to the square of the distance between them. This is shown in equation 1;
[tex]F =G \frac{m_{1} X m_{2} }{d^{2} }[/tex]............ 1
Where F is the gravitational force = 0.0001 N
G is the gravitational constant = 6.673 x [tex]10^{-11} Nm^{2} kg^{-2}[/tex]
[tex]m_{1}[/tex] is the mass of the compact car = 900kg
[tex]m_{2}[/tex] is the mass of the pickup truck = 1600kg
d is the distance and its unknown ?
Let us make d the subject formula in equation 1
[tex]d = \sqrt{G\frac{m_{1} m_{2} }{F } }[/tex] .... 2
Substituting into equation 2 we have
[tex]d = \sqrt{\frac{6.673x10^{-11} x 900 x 1600}{0.0001N} }[/tex]
d = 0.96048m
Therefore the distance between the compact car and pickup truck is 0.96048 m
What is the initial vertical velocity of the ball?
A.
0 m/s
B.
9.81 m/s
C.
20.0 m/s
D.
60.0 m/s
Light travels from a
laser across an 8 m
room where it reflects
off a mirror. Uniform or non uniform velocity
Answer:
Non-uniform velocity as the laser light beam has got reflected by the mirror
And as the light got reflected there is a change in velocity making it non-uniform velocity
An element or compound used to enhance a semiconductor is called a(n) ____.
The element named boron can be used to enhance the properties of semiconductors.
What is a semiconductor?A semiconductor is a material that has electronic properties and has the value that falls in between a conductor. It can be a metallic copper or an insulator.
The rise in temperatures leads to a fall in resistivity. The element named boron can improve the electrical properties of the semiconductor as they form the impurities.
Find out more information about the element.
brainly.com/question/12389810
in the case shown below, the 1 kg rock rides on a horizontal disk that rotates at constant speed 5m/s
Answer:25 N
Explanation:
in the case shown below, the 1 kg rock rides on a horizontal disk that rotates at constant speed 5m/s is 25N
what is speed ?Speed is the ratio of distance with respect to the time in which the distance was covered. Speed is a scalar quantity as it does not have magnitude only have direction
The formula of speed can be represented as s=d/t, Where, s is the speed in m.s-1, d is the distance traveled in m, t is the time taken in s
Uniform speed is defined when the object covers equal distance at equal time intervals, variable speed is defined as when the object covers a different distance at equal intervals of times.
Average speed is defined as the total distance travelled by an object to the total time taken by the object.
Instantaneous speed is defined as when the object is move with variable speed, then the speed at any instant of time is known as instantaneous speed.
For more details regarding speed, visit
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A projectile is fired horizontally from a height of 10 m above level ground. The projectile lands a horizontal distance of 15 m from where it was launched.
-Find the hang time for the projectile.
-Find the initial speed of a projectile.
-What are the x and y components of the projectile’s velocity the moment before it strikes the ground?
-At what speed will the projectile strike the ground?
Answer:
a)t = 1,43 s
b) V = 10,49 m/s
c) V₀ₓ = 10,49 m/s ; V₀y = 14,01 m/s
d) Vf = 17,5 m/s
Explanation:
According to the problem statement
V₀ = V₀ₓ and V₀y = 0
And at the end of the movement t = ? the distance y = 10 m
Therefore as
h = V₀y - (1/2)*g*t²
Vertical distance y = h = 10 = V₀y*t - 0,5 (-9,8)*t²
10 = 4,9*t²
t² = 10/4,9 ⇒ t² = 2,04 s
t = 1,43 s
a) 1,43 s is the time of movement
b) V₀ = V₀ₓ V₀y = 0 and V₀ₓ = Vₓ ( constant )
Just before touching the ground, the horizontal distance is
hd = 15 = Vₓ * t
Then 15 /1,43 = Vₓ = V₀ₓ
Vₓ = 10,49 m/s
Then initial speed is V = 10,49 m/s since V₀y = 0
Vf² = Vₓ² + Vy²
Vyf = V₀y - g*t
Vyf = 0 - 9,8 *1,43
Vyf = - 14,01 m/s
And finally the speed when the projectile strike the ground is:
Vf² = Vₓ² + Vy²
Vf = √ (10,49)² + (14,01)²
Vf = 17,50 m/s
Which is the largest gas that occurs in our atmosphere?
Helium
Nitrogen
Other Gases
Oxygen
Answer:
OXYGEN
Explanation:brainlyist me
Answer:
Nitrogen
Explanation:
Oxygen is second
How high does a rocket have to go above the earth's surface to be subject to a gravitational field from the earth that is 50.0 percent of its value at the earth's surface?
A) 2.650 km
B) 3,190 km
C) 9.020 km
D) 12.700 km
Answer:
A) 2.650 km
Explanation:
The relationship between acceleration of gravity and gravitational constant is:
[tex]g = \frac{Gm}{R^2}[/tex] ---- (1)
Where
[tex]R = 6,400 km[/tex] -- Radius of the earth.
From the question, we understand that the gravitational field of the rocket is 50% of its original value.
This means that:
[tex]g_{rocket} = 50\% * g[/tex]
[tex]g_{rocket} = 0.50 * g[/tex]
[tex]g_{rocket} = 0.5g[/tex]
For the rocket, we have:
[tex]g_{rocket} = \frac{Gm}{r^2}[/tex]
Where r represent the distance between the rocket and the center of the earth.
Substitute 0.5g for g rocket
[tex]0.5g = \frac{Gm}{r^2}[/tex] --- (2)
Divide (1) by (2)
[tex]\frac{g}{0.5g} = \frac{Gm}{R^2}/\frac{Gm}{r^2}[/tex]
[tex]\frac{g}{0.5g} = \frac{Gm}{R^2}*\frac{r^2}{Gm}[/tex]
[tex]\frac{1}{0.5} = \frac{1}{R^2}*\frac{r^2}{1}[/tex]
[tex]2 = \frac{r^2}{R^2}[/tex]
Take square root of both sides
[tex]\sqrt 2 = \frac{r}{R}[/tex]
Make r the subject
[tex]r = R * \sqrt 2[/tex]
Substitute [tex]R = 6,400 km[/tex]
[tex]r = 6400km * \sqrt 2[/tex]
[tex]r = 6400km * 1.414[/tex]
[tex]r = 9 049.6\ km[/tex]
The distance (d) from the earth surface is calculated as thus;
[tex]d = r - R[/tex]
[tex]d = 9049.6\ km - 6400\ km[/tex]
[tex]d = 2649.6\ km[/tex]
[tex]d = 2650\ km[/tex] --- approximated
As a bicycle is ridden west in a straight line with decreasing speed,the acceleration of the bicycle must be
Answer:
Decreasing
Hope this helps! :)
What would its weight be on Jupiter?
24.9N
Answer:
1.898 × 10^27 kg
Explanation:
thats how much it ways
3
4
Lucy runs 4 meters to the east, then 5 meters south. What is the magnitude of her displacement?
Show Your Work
Answer:
The displacement is 6.4m
Explanation:
Step one:
given
we are told that Lucy runs 4 meters to the east,
then 5 meters south.
let the distance east be the displacement in the x-direction, and south be the y-direction
Step two:
The resultant of the x and y displacement is the magnitude of the total displacement z
applying Pythagoras theorem we have
z=√x^2+y^2
z=√4^2+5^2
z=√16+25
z=√41
z=6.4m
A golf ball flies through the air after being struck with a golf club. Which of the following statements describes the force on the ball as momentum is transferred between the club and ball?
A. The ball does not experience any force.
B. The force experienced by the ball is greater than the force experienced by the club.
C. The force experienced by the ball equals the force experienced by the club.
D. The force experienced by the ball is weaker than the force experienced by the club.
Answer:
C) The force experienced by the ball equals the force experienced by the club.
Explanation:
When the golfer strikes the ball with his club, the club exerts a force on the ball. Due to Newton's Third Law Of Motion [Every Action has an equal and opposite reaction], the ball also exerts an equal force on the club. However,
As the mass of the club is usually greater than the mass of the ball, it accelerates slower; While the ball way faster, following the equation : F=ma
A 100kg couch is being pushed with 196N of force. As it slides along the ground it experiences a coefficient of friction of 0.1. What is the net force in this situation?
A 300N
B 202N
C 398N
D 98N
Answer:98
Explanation:hope this helps!
The fact that our preconceived ideas contribute to our ability to process new information best illustrates the importance of: the serial position effect. O repression iconic memory . semantic encoding . retroactive interference .
Answer:
It’s a
Explanation:
Don’t actually put that i needed the points mb
Hey guys this is Ap physics please help I need this to pass i will mark brainliest for a good attempt
Split up the forces into components acting parallel to and perpendicular to the slope. See the attached picture for the reference axes.
The box stays on the surface of the plane, so that the net force acting perpendicular to it is 0, and the only acceleration is applied in the parallel direction.
Let m be the mass of the box, θ the angle the plane makes with the ground, and a the acceleration of the box. By Newton's second law, we have
• net parallel force
∑ Force (//) = W (//) - F = m a
(that is, the net force in the parallel direction is the sum of the parallel component of the weight W and the friction F which acts in the negative direction)
• net perpendicular force
∑ Force (⟂) = W (⟂) + N = 0
Notice that
W (//) = W sin(θ) … … … which is positive since it points down the plane
W (⟂) = -W cos(θ) … … … which is negative since it points opposite the normal force N
So the equations become
W sin(θ) - F = m a
-W cos(θ) + N = 0
Solving for a gives
a = (W sin(θ) - F ) / m
which is good enough if you know the magnitude of the friction force.
If you don't, you can write F in terms of the coefficient of kinetic friction between the box and plane, µ, as
F = µ N
so that
a = (W sin(θ) - µ N ) / m
and the normal force itself has a magnitude of
N = W cos(θ)
so that
a = (W sin(θ) - µ W cos(θ) ) / m
The weight W has magnitude m g, where g is the magnitude of the acceleration due to gravity, so
a = (m g sin(θ) - µ m g cos(θ) ) / m
a = g (sin(θ) - µ cos(θ))