Answer:
While making a bridge or a building, the first thing that comes to our mind is that these are always made by the combination of concrete and steel. Concrete is cheap, but it has the property of breaking when it is twisted or under tension. Steel is expensive, If we made the whole thing with it, it will cost a lot. To provide strength under a reasonable cost, we use the combination of concrete and steel. Another postive point which they have together is that they both expand equally under heat, because they have the same coefficient of thermal expansion. It proves really useful, because if they had different coefficients of thermal expansions, one would expand more than the other, which will create tensions in the mixture and would break it easily. In the case, many cracks would start to appear in the bridge or buildings, which will eventually break them.
A 31.7 kg kid, initially at rest, slides
down a frictionless water slide at 53.2º.
How fast is she moving 3.45 s later?
Answer:
34.55m/s
Explanation:
Now from Newton's law of motion;
V= U+ a×t
V- final velocity
U- initial velocity = 0m/s
a- acceleration
t- time
Note that a = g/cos53.2°
Now g is acceleration of free fall due to gravity
This is a vertical acceleration since the course of motion is along a plane inclined at 53.2° to the height of the pool.
Also from trigonometry identity
cos 53.2°= vertical component a/ acceleration ( cos a = adjacent/hypothenus)
If we assume g = 9.8m/S2 { a generally given value}
Substituting t = 3.45s as the time of consideration, we have;
V = 0 + (9.8/cos53.2°)×3.45
= -34.55m/s
Note the -ve sign is just telling us this velocity is causing the object to move down.
Hence V = 34.55m/s
Answer:
27.07 m/s
Explanation:
this is the right answer
Njoki planted trees at intervals of 22m apart on the diagonal of a rectangular plot of land that measures 48m by 20m . How many trees did he plant
Answer:
The number of tree is 2Explanation:
the diagonal of the rectangular plot of land can be found using Pythagoras theorem (the diagonal is the hypotenuse)
Given
length of land x= 48m
width of land y= 20m
digonal z= ?
[tex]z^2= x^2+y^2\\\\z=\sqrt{ x^2+y^2} \\[/tex]
substituting the values of x and y into the equation we can solve for z
[tex]z=\sqrt{ 48^2+20^2} \\\\z=\sqrt{ 2304+400} \\z=\sqrt{ 2704} \\z=52m\\[/tex]
The diagonal is 52m
Hence since the interval = 22m the number if treee is
[tex]\frac{52}{22} = 2.36\\[/tex]
The number of trees must be whole numbers , the number of tree is 2
1a. Assuming 100% efficient energy conversion, how much water stored behind a 50cm high hydroelectric dam would be required to charge a 50 ampere-minute 12 volt battery with 600j of energy stored in it
Answer:
7.22 m³ of water should be stored behind the hydroelectric dam.
Explanation:
First we find the total energy that can be stored in the battery. For that purpose we use the formula:
P = VI
where,
P = Power delivered by battery
V = Voltage of Battery = 12 volts
I = Current in Battery
Multiplying both sides by time interval (t), we get:
Pt = VIt
where,
Pt = (Power)(Time) = Total Energy Stored in Battery = E = ?
It = Current Rating of Battery = (50 A.min)(60 s/min) = 3000 A.s
Therefore,
E = (12 volt)(3000 A.s)
E = 36000 J
Now, we have to find the energy required to fully charge the battery:
Energy Required = ΔE = Total Energy Capacity(E) - Already Stored Energy
ΔE = 36000 J - 600 J
ΔE = 35400 J
Now, this energy must be equal to the potential energy of water stored behind hydroelectric dam to fully charge the battery, provided that the conversion efficiency is 100 %.
Therefore,
ΔE = mgh
where,
m = mass of water behind hydroelectric dam
g = 9.8 m/s²
h = height of dam = 50 cm = 0.5 m
Therefore,
35400 J = m(9.8 m/s²)(0.5 m)
m = (35400 J)/(4.9 m²/s²)
m = 7224.5 kg
Now, to find the volume of stored water, we use:
ρ = m/V
V = m/ρ
where,
ρ = density of water = 1000 kg/m³
V = Volume of water behind dam = ?
V = (7224.5 kg)/(1000 kg/m³)
V = 7.22 m³
What are some advantages
and disadvantages to using
superconductors as electric
transmission lines
Answer:
Insulators show very high resistance to electricity. Conductors like copper show some resistance. Another class of materials show no resistance at all when cooled to very low temperatures, cooler than the coolest deep freezer. Called superconductors, they were discovered in 1911.
Explanation: i looked it up
What is the symbol for Pressure ? Help
Answer:
The answer is Pascal or Pa.
Answer:
Pa or small p
Explanation:
Force over Area. The SI unit is Pascal
the components and functionality of the event horizon telescope.
Answer:
The Event Horizon Telescope comprises of a an interconnection of radio observatories. These radio observatories work in unison and helps in efficient observation of radio sources associated with black holes with angular resolution in comparison to their event horizons. This equipment functions by ensuring that anything or light which goes through the event horizon cannot escape from the black hole. Instead there will be a continual falling towards the center of the black hole.
if a rock has a speed of 12 m/s as it hits the ground, from what height did it fall assuming the speed was zero.its mass is 50 kg
Answer:
a=9.8 ms−2 12^2=0^2+2×9.8×H
H=7.35m
Explanation:
To find the height the following formula should be used: v2=u2+2aH
Assuming this occurs on earth,
Answer:
7.3 m
Explanation:
QUICK WILL MARK BRAINLIEST
As light shines from air to water, the index of refraction is 1.02 and the angle of
incidence is 38.0 °. What is the light's angle of refraction?
29.8°
32.5°
37.1°
39.8°
Answer:
37.1°
Explanation:
How many meters is in 32 km
Answer:
32000 m
Explanation:
1000m in 1 km, so 32000m in 32 km.
Answer:
32000m
Explanation:
1km=1000m
so 32 kn is equals to 32000m
8. Simple machines make a job easier to perform by
a. decreasing the amount of work
b. decreasing the amount of friction
c. decreasing the amount of force and/or changing the direction of force
d. only lower the amount of force
Answer:
C
Explanation:
Please answer these: Q1. i. In what two ways combustion can be useful to us? Explain by giving examples. ii. Explain why decomposition of sugar on heating is an irreversible change. Q2. In order to answer this question you need to look around your immediate surroundings to find examples of rusting of iron or any other metal. i. What makes iron rust? ii. Why is the rusting of iron a problem? Give any 3 examples from daily life where rusting has been a disadvantage. iii. Suggest any two ways that can help prevent rusting of iron. Q3. i. Give two differences between a physical change and a chemical change. ii. Explain whether condensation of water vapour is a physical or a chemical change. iii. Write word equations for the following reactions: a. Breaking down/ electrolysis of water b. synthesis of water c. decomposition of sugar d. photosynthesis in plants
Answer:
1) combustion can be used as a source of energy.
Combustion is used to power rockets
ii) Decomposition of sugar is a chemical change and new substances are formed.
2)corrosion of pipes
Corrosion of bridges
Corrosion of knives and blades at home
I) iron rusts due to the action of air and moisture bon the metal setting up an electrochemical process in which the iron is the anode. This leads to the corrosion of the iron metal.
ii) Rusting is a problem because it reduces the economic value of iron. Rust weakens iron and threatens the integrity of materials made from iron.
Iron rusting may lead to the collapse of a bridge
Iron rusting makes a blade blunt
Iron rusting weakens pipes made of iron
iii) Rusting of iron can be prevented by galvanizing the iron or by painting the iron.
3) chemical change leads to the formation of a new substance while physical change does not lead to the formation of a new substance.
Chemical changes are not easily reversible while physical changes are easily reversible.
ii)condensation of water vapour is a physical change
iii)
Electrolysis of water;
Two moles of water---> two moles of hydrogen gas + one mole of oxygen gas
Synthesis of water;
two moles of hydrogen gas + one mole of oxygen gas---->Two moles of water
Decomposition of sugar;
One mole of Sucrose---> twelve moles of carbon + eleven moles of water + heat
Six moles of carbon dioxide + six moles of water +energy------> one mole of sugar + six moles of oxygen
Explanation:
Combustion is useful as a source of energy because it is used in power generation. Currently, combustion is being used to power rockets. It is also used as a way of providing heat at home.
One of the characteristics of a chemical change is that it leads to the formation of new substances. Since the decomposition of sugar leads to the formation of carbon and water, it is an irreversible chemical change.
When water is heated, it is converted into vapour which can settle on a surface and convert back to liquid water. This is a physical change.
A 50 - N x m torque acts on a wheel with a moment of inertia 150 kg x m² . If the wheel starts from rest , how long will it take the wheel to make one revolution ?
Answer:
t = 6.17 s
Explanation:
For a 1 revolution movement, [tex]\triangle \theta = 2\pi[/tex]
Torque, [tex]\tau = 50 Nm[/tex]
Moment of Inertia, [tex]I = 150 kg m^2[/tex]
If the wheel starts from rest, [tex]w_{0} = 0 rad/s[/tex]
The angular displacement of the wheel can be given by the formula:
[tex]\triangle \theta = \omega_0 t + 0.5 \alpha t^2[/tex]................(1)
Where [tex]\alpha[/tex] is the angular acceleration
[tex]\tau = I \alpha\\\alpha = \frac{\tau}{I} \\\alpha = 50/150\\\alpha = 0.33 rad/s^2[/tex]
To get t, put all necessary parameters into equation (1)
[tex]2\pi = 0(t) + 0.5(0.33)t^2\\2\pi =0.5(0.33)t^2\\t^2 = \frac{4 \pi}{0.33} \\t^2 = 38.08\\t = 6.17 s[/tex]
the weight of a body of certain mass become zero in space.why?
Answer:
There is no force in space.
Explanation:
Weight is the gravitational force acting on the mass as in space there is no gravity so weight appeares as zero
Answer:
It is because of gravity that your weight of a certain mass becomes zero in space.
Explanation:
*
A light year is
1 Point
O 365 days
O The distance light travels in a year
O The distance from Earth to Proxima Centauri
Helppp now is my final exammmm pleaseeee
Answer:
2.The Distance Light Travels In A Year
Explanation:
A Light Year Is Nothing But The Distance That The Light Travels In Onw Year
Answer:
Shown from explanation.
Explanation:
Light year is the distance light travels in one year and you can calculate that.
Light travels 3× 10^8m in 1 second; so you calculate the number of seconds in 365days and multiply by 3× 10^8m.
Light year was a unit of measure derived by man for expressing planetary distances due to their so huge distance which goes beyond our scale of measure.
Explain the following behaviour of molecules water rises up in a harrow tubes but mercury which is also a liquid falls in a narrow tubes to level below the outside surface
Answer: find the answer in the explanation
Explanation:
The capillarity of water molecules is different from the mercury molecules.
What is capillarity ?
This is the tendency of a liquid substance to rise in a capillary tube.
Molecules water rises up in a harrow tubes because of the force of adhesion between the water molecules and the tube molecules is greater than the force of cohesion between the water molecules. This helps water to wet the tube and rise. While mercury which is also a liquid falls in a narrow tubes to level below the outside surface because the force of cohesion between the mercury molecules is greater than the force of adhesion between the mercury molecules and the tube molecules. Mercury does not wet.
would iron and carbon from metallic bonds
Answer:
NO
Explanation:
Since iron is a metal and carbon is a non- metal, they cannot form a metallic bond.
what is the capital of Ghana and also Togo.
Answer:Ghana - Accra Togo - Lomé I hope this helps mark me brainlist
Explanation:
Accra is the Capital of Ghana
Accra was founded in the 17th century by the Ga people. It became the capital of the British Gold Coast in 1877 and the capital of Ghana on the formation of the country as an independent state in 1957
Accra Is the Second Most Expensive City in Africa
Accra is known for its colorful textile and used or second-hand clothing markets. Located inside the Makola Market, Kantamanto is the largest trading point in all of Accra.
The capital of Togo is Lomé
Lomé, city, capital of Togo. Lomé lies on the Gulf of Guinea (Atlantic coast) in the extreme southwestern corner of the country. Selected as the colonial capital of German Togoland in 1897, it became important as an administrative, commercial, and transport centre.
It is also the country's chief port, from where it exports coffee, cocoa, copra, and oil palm kernels- Lome
Lomé was founded by the Ewe, an indigenous ethnic group, in 1880. Located on the southwestern Atlantic coast of Togo, Lomé has a long history of trade. In 2000, an estimated 900,000 people resided in Lomé. Europe's “Scramble for Africa” began in 1880.
Rhodes research indicates that people are generally accurate in guessing the ages of unfamiliar persons based on their faces. This research has important implications for
The available options are:
A. bartenders serving alcohol
B. students identifying their professors.
C. Doctors diagnosing cases of schizophrenia.
D. eyewitnesses identifying suspects from a lineup.
Answer:
A. bartenders serving alcohol
Explanation:
This is because of the underage rule concerning sale of alcohol. Thus, there are occasional period in which underage person or a minor will want to buy alcohol, and without necessarily asking for the birth certificate or ID card that contains Age information, it is therefore, necessary for bartenders to be able to tell the age of their unfamiliar customers, by mere looking at them, so as not to sell to a minor.
Hemce, Rhodes research in guessing the age of unfamiliar person has important implications for BARTENDERS SERVING ALCOHOL, because it will guide them to determine Underage or Minor, that want to buy alcohol from them.
Please help
Right answers please
Will mark brainliest
Answer:
a. 45 N. / b. 0.08 m/s^2. / c. 102 N
F = ma
F = 15(3)
F = 45 newtons
F/m = a
20/250 = a
0.08 m/s^2 = a
R = ma
R =1.5(68)
102 N
this principle is useful in solar cooker but can be harmful on earth?
Answer:
Green House Effect
Explanation:
Green House Effect is the principle used in solar cookers but it can be really harmful for the Earth producing some green house gases.
What is the magnitude of impulse of a 2.7 gram ping pong ball initially moving at 15 m/s, if hit by a ping pong paddle and then moves the opposite direction at 14/ms
Answer:
impulse = 0.0783 kg.m/s
Explanation:
The impulse is the product of the force and an interval of time. This can be represented in terms of the mass of the body and the change in the velocity of the body in such a time:
[tex]F\Delta t=m\Delta v[/tex] [tex]=|m(v_f-v_i)|[/tex]
m: mass of the body = 2.7gm = 0.0027 kg
vf: final velocity = -14m/s
vi: initial velocity = 15m/s
vf is negative because the direction of the ball is opposite to the initial direction:
[tex]|m(v_f-v_i)|=|(0.0027kg)(-14m/s-15m/s)|=0.0783\frac{kg.m}{s}[/tex]
hence, the impulse of the ping pong ball is 0.0783 kg.m/s
Un movil pasa por el punto A en direccion hacia B (350cm más adelante) y, luego, sigue hasta el punto C. Sabiendo que pasa por B a las 11:42:38 y por C a las 11:43:16, completando un tiempo total de recorrido de 3min 47s, calule la distancia entre B y C y a la hora a la que paso por el punto A.
Explanation:
PRIMERO HACES EL RECUENTO DEL TIEMPO Y LO CONVIERTES EN
SEGUNDOS Y ENTONCES
t = 227 s [tex]t_{AB}[/tex] = 227 S - 38 s = 189 s
[tex]t_{BC}[/tex] = 38 s
LUEGO USANDO LA ECUACIÓN DE GALILEO GALILEI SSUPONIENDO
QUE EL MOVIL VIAJA A VELOCIDAD CONSTANTE
v = 3.50 m/189 s = 0.0185 m/s
PARA LA DISTANCIA NTRE B Y C
[tex]x_{BC}[/tex] = 0.0185 m/S( 38 s) = 0.703 m
LA HORA EN QUE EL MOVIL PASA POR A ES
11:43:15 - 38 s - 189 s = 11:39:29
I beggggg youu to solve this for me, I'm giving you 60 POINTS !!!
please solve it on a paper and send it i should submit it tomorrow it's graded
Answer:
but where is the question ?
Explanation:
hope it works out
Answer:
where the question about?
Explanation:
I think the question is invisible
A rocket is launched from atop a 101 foot cliff with an initial velocity of 116 ft/s.
\a. Substitute the values into the vertical motion formula h(t) = -16t2 + vt + h0 . Let h(t) = 0
b. How long will the rocket take to hit the ground after it is launched? Round to the nearest tenth of a second.
Answer:
A. 16t2 -116t -101=0 B. 8.0s
Explanation:
Known parameters from the question:
Height of Cliff,h0 = 101ft
Velocity of rocket ,v= 116ft/s.
1.Substituting the above to the above formula we have;
h(t) = -16t2 + vt + h0
Since h(t) =0, it means the rocket is falling towards the ground, when it gets to the ground when it's at rest the height h(t) = 0m
{Note the rocket is launched from the height of the Cliff so that would be the initial height of the rocket,h0}
2.Substituting into h(t) = -16t2 + vt + h0
We have;
0 = -16t2 + 116t + 101=> 16t2 -116t -101=0
Using formula method for solving quadratic equation we have;
t = -(-116)+_√[(-116)^2 -( 4× 16 ×-101]/ (2× 16)
t = [116 +_(141.1382)]/32
t = (116 -141.1382)/32 or (116 +141.1382)/32
-0.786s or 8.036s
-0.8s or 8.0s to the nearest tenth.
Now time cannot be negative in real life situation hence the time is 8.0s
Note : the general equation of a quadratic equation with variable t is given below;
at2 + bt + c=0
Formula method for quadratic equation is :
t =( -b+_√[(b^2 -( 4× a×c)] ) / (2× a)
What do nuclear fission and nuclear fusion have in common?
A. They start with the same reactants.
B. They're both used in power plants.
C. Their products have more mass than their reactants.
D. Their products have less mass than their reactants.
Answer:
B
Explanation:
Fission and Fission are nuclear reaction processes that releases energy.
Fission is the process where the nuclei of an atom splits into smaller nuclei of same element or elements of smaller nuclei when Fussion is when two smaller nuclei combined to form one of a different element of a higher nuclei. These processes release energy.
Answer:
D. Their products have less mass than their reactants.
Explanation:
Earth is a dynamic system what exactly does this mean
Answer:
The answer to the following question is given below.
Explanation:
This means a mixture of interconnected, interlinked, or interactive elements that establish the collaborative entity or entities.
The Earth system manages to maintain its very presence on even a macro level as well as processes in general thru the engagement of all its elements. This affects such as erosion, whereas others happen unexpectedly, such as an earthquake. It is crucial to keep our lifestyle in mind that we can recognize all such adjustments as well as their implications.a diode can be used as a rectifier. what is the function of a rectifier?
Explanation:
Rectifier diodes are used in power supplies to convert alternating current (AC) to direct current (DC), a process called rectification. They are also used elsewhere in circuits where a large current must pass through the diode.
Please explain how you got the answer :(
Answer:
36.5 kJ
Explanation:
Energy by machine = energy to machine × efficiency
E = 52.1 kJ × 0.70
E = 36.5 kJ
In a hydroelectric power station, how much potential energy is lost by 100tonnes of water flowing down through the pipes, falling a vertical distance of 200metres? [1tonne=1000kg.]
Answer:
196000000 J
Explanation:
Potential Energy: This can be defined as the energy of a body due to its position in the gravitational field.
From the question,
P.E = mgh.................. Equation 1
Where P.E = potential Energy, m = mass of the water, h = height, g = acceleration due to gravity.
Given: m = 100 tonnes = (100×1000) = 100000 kg, h = 200 m
Constant: g = 9.8 m/s²
Substitute into equation 1
P.E = 100000(200)(9.8)
P.E = 196000000 J.
Note: When a object falls through a height he losses its potential energy.
Hence the potential energy lost = 196000000 J = 196 MJ.
plzzzzzzz help me quick
Explanation:
in the first thing we are allowing bacteria to grow
in the second one we are killing it