According to astronomers, the whole universe started with a giant explosion called as Big Bang. Big Bang theory shows that the universe is extended from high density state. It says that universe is made up of a single point, which stretched and explodes out and is still stretching.
There are some evidences for big bang, they are:
1) There are some red shifts of different galaxies which means that the universe is expanding.
2) Due to the expanding of universe, some of the new elements are created like hydrogen, deuterium, etc.
3) Microwaves are detected by orbiting detectors.
Thus, these parameters show that Big Bang theory is correct.
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A roller-coaster goes over an 13 m tall hill then approaches a 26 m hill. What is the minimum velocity the roller-coaster would need when going over the 13 m hill to make it to the top of the 26 m hill?
The minimum velocity the roller-coaster would need when going over the 13 m hill to make it to the top of the 26 m hill is 16.56 m/s.
What is force?Force is defined as the physical quantity or the power.
the normal force would havening to point away from the group center of the curve. Unless they have belts, the riders will fall from the cars.
In a teardrop-shaped in the continuous loop the radius of curvature r decreases, causing them centripetal acceleration to increase. The speed would be decrease as the car rises (because of gravity), but it is they are
overall by the effect is that the required centripetal force of the increases, meaning is the normal force increased there is less danger if not to the wearing a seat belt.
Suppose the minimum velocity is v.
Then mechanical energy at top of 13m hill is:
0.5 mv² + mgh
= 0.5 mv² + 15mg
g = 9.81 m/s/s (acceleration due to gravity).
All of this (assuming no loss due to friction) is converted to potential energy at top of 29m hill
So,
0.5 m v² + 15mg = 29mg
0.5 m v² = 14 mg
v² = (14 × 9.8)/0.5
v² = 274.4
v = 16.56 m/s
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the efficiency of a solar cell is defined as the percentage of the total energy input that does useful work. t or f
The efficiency of a solar cell is defined as the percentage of the total energy input that does useful work. Hence, this statement is true.
Efficiency of a solar cell refers to the ratio of solar cell result to input energy from the sun rays. Efficiency means an indicator that is used to compare the presentation of one solar cell to another. Efficient energy can be described as the process of make the amount of energy required to provide products and services become less than before. The example of efficient energy is insulating a building lets it to make less heating and cooling energy to get and maintain a thermal comfort. Energy-efficient homes and buildings use energy to heat a bit, cool, and run appliances and electronics, and energy-efficient manufacturing facilities use a bit energy to create items.
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True/False: The rise in global temperatures over the last century can be explained by planetary motions
The rise in global temperatures over the last century can be explained by planetary motions that are false.
What is global temperature rise?Global warming is an event where there is an increase in temperature in the atmosphere and the earth's surface (global temperature). An increase in temperature on earth will certainly have a considerable impact and cause a change in the ecological order of life.
Global warming occurs due to the process of increasing the average temperature of the atmosphere, sea, and earth's land. This phenomenon is triggered by human activities, especially those related to the use of fossil materials and land use change activities.
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A group of students prepare for a robotic competition and build a robot that can launch large spheres of mass M in the horizontal direction with variable speed and from a variable vertical position and a fixed horizontal position x=0.
The robot is calibrated by adjusting the speed at which the sphere is launched and the height of the robot’s sphere launcher. Depending on where the spheres land on the ground, students earn points based on the accuracy of the robot. The robot is calibrated so that when the spheres are launched from a vertical position y=H and speed v0, they consistently land on the ground on a target that is at a position x=D. Positive directions for vector quantities are indicated in the figure.
When the students arrive at the competition, it is determined that the height of the sphere launcher can no longer be adjusted due to a mechanical malfunction. Therefore, the spheres must be launched at a vertical position of y=H2. However, the spheres may be launched at speed v0 or 2v0.
Question: In a clear response that may also contain diagrams and/or equations, describe which speed, v0 or 2v0, the students should launch the sphere at so that they earn the maximum number of points in the competition.
Free fall motion is motion in which the only force acting on the body is gravity.
What is free fall motion?A free-falling object is one that moves only due to the effect of gravity, and its motion is defined by Newton's second law of motion. We can use algebra to calculate the acceleration of a free-falling particle.
The student should launch the sphere at 2v₀, for the sphere will land at approximately 1.41D, which is in the 3 point zone
The given parameter are;
The distance covered by the sphere when launched at height, H = D
The velocity with which the ball reaches D = v₀
The current available height of launcher= H/2
The available velocities = v₀, and 2v₀
Now,
From H = ut + (1/2)gt², where, initial velocity of the vertical motion of the ball, u = 0
we know;
H = (1/2)gt²
Therefore, the time it takes the ball to drop from H, t = √(2H/g)
The distance, D = v₀ × √(2H/g)
When the height is H/2, we get;
t = √(2H/(2g)) = √(H/g)
Thus, the distance covered, D₁ = v₀ × √(H/g)
Therefore, D = (√2) × v₀ × √(H/g) = (√(2))D₁
Now, D₁ = D/(√2) ≈ 0.71D
D₁ ≈ 0.71D
At speed 2v₀, we have;
D₂ = 2v₀ × √(H/g) = √2 × v2 × v₀ × √(H/g) = √2 × v₀ × √(2H/g) = √2D₁ ≈ 1.41D
D₂ ≈ 1.41D
The 2 point zone = D/2 < x < D = 0.5D < x < D (Position D₁ ≈ 0.71D is located here)
The 3 Point Zone = D < x < 3D/2 = D < x < 1.5D (Position D₂ ≈ 1.41D is located here)
Given that at D₂, the ball lands in the 3 Point Zone, the student should launch the sphere at the speed, 2v₀, so that the ball will land at D₂ ≈ 1.41D, which is in the 3 Point Zone
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The complete question is as follows:
A group of students prepare for a robotic competition and build a robot that can launch large spheres of mass M in the horizontal direction with variable speed and from a variable vertical position and a fixed horizontal position x=0.
The robot is calibrated by adjusting the speed at which the sphere is launched and the height of the robot’s sphere launcher. Depending on where the spheres land on the ground, students earn points based on the accuracy of the robot. The robot is calibrated so that when the spheres are launched from a vertical position y=H and speed v0, they consistently land on the ground on a target that is at a position x=D. Positive directions for vector quantities are indicated in the figure.
When the students arrive at the competition, it is determined that the height of the sphere launcher can no longer be adjusted due to a mechanical malfunction. Therefore, the spheres must be launched at a vertical position of y=H2. However, the spheres may be launched at speed v0 or 2v0.
Question: In a clear response that may also contain diagrams and/or equations, describe which speed, v0 or 2v0, the students should launch the sphere at so that they earn the maximum number of points in the competition.
because of the pressure inside a popcorn kernel, water does not vaporize at 100°C. Instead, it stays liquid until its temperature is about 175°C, at which point the kernel ruptures and the superheated water turns into steam. How much energy is needed to pop 95.0 g of corn if 14 percent of a kernel's mass consists of water? Assume that the latent heat of vapor- ization for water at 175°C is 0.90 times its value at 100°C and that the kernels have an initial temperature of 175°C.
The energy needed is 35.4 KJ, to pop the corn of a given quantity, and by using latent heat of vaporization of water.
What is Energy?
When work is done and heat and light are produced, energy is the quantitative quality that is transferred to the body or to the physical system. The law of conservation of energy asserts that although energy can be changed in form, it cannot be created or destroyed. Energy is a conserved quantity.
Calculations:
The boiling point of water is 175 °C.
The mass of corn is 95.0 g.
The percentage of water in corn is 14%.
The latent heat of vaporization for water at 175 °C is 0.90 times its value at 100 °C.
Calculate the mass of water,
Mw = (14/100) × (95g) × (1kg/1000g)
= 0.0133 Kg
calculate the latent heat of vapourization,
Lv = (0.9) × (2.26 × [tex]10^{6}[/tex]J/kg)
= 2.034 × [tex]10^{6}[/tex] J/kg
Total heat required,
Q = Mw Lv + Mw. C Δ T
Substitute the values,
Q = (0.0133) × (2.034 × [tex]10^{6}[/tex]) + (0.0133) × (4186) × (175.25)
= (35403.27 J) × ( 1KJ/ 1000J)
= 35.4 KJ
Hence, the energy needed is 35.4 KJ, to pop the corn of a given quantity.
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An oven with a convection setting has a fan and vent system that keeps air moving around inside of the oven. Conventional ovens do not have this type of system. Joelle claims that convection ovens cook food more quickly and evenly.
A) Construct an explanation for this claim
B) suggest how you could test this claim and support your explanation. Which variables would you control?
As the air flows through convection oven, the required temperature less for this type of oven and convection ovens cook food more quickly and evenly.
What is efficiency of convection oven?Compared to a traditional oven, a convection oven enables a reduction in cooking temperature. This comparison will change based on various elements, such as the quantity of food being cooked at once or when airflow is being impeded, such as by an excessively large baking tray.
The fact that flowing air transfers heat more quickly than still air of the same temperature balances out this variation in cooking temperature. The temperature must be lowered to slow down the rate of heat transfer in order to transfer the same quantity of heat in the same length of time.
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In the district soccer championship finals, Elizabeth kicks a 0.75 kg soccer ball with a force of 17.0 N. How much does she accelerate the soccer ball from rest in the process?
22.6m/s² will be the Acceleration needed by Elizabeth.
According to Newton's second law of motion, the force is equal to the product of the mass and acceleration of an object.
So the formula used will be,
F = ma
then, a = F/m
Where a is acceleration, F is force and m is the mass of the ball.
Then
a = 17/0.75 = 22.6
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Zoe finds that the temperature of a substance is 12 degrees Celsius. What does this tell Zoe about the substance?
What this tells Zoe about the substance is that 12 degrees Celsius is the average kinetic energy of the substance.
What is temperature of a substance?
The temperature of a substance is defined as the average kinetic energy of all the atoms or molecules of that substance.
Also, the temperature of a substance is the measure of the degree of hotness or coldness of the substance.
The temperature of a substance can be measured with different units and they include the following;
KelvinCelsiusFahrenheitThus, the temperature of a substance tells about the average kinetic energy of the substance or the degree of hotness or coldness of the substance.
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3) A body of mass 10 kg is pulled from rest with a constant force of 40 N. The force is applied for 2 sec. calculate (a) The distance travelled (b) Work done on the body (c) The KE of the body (d) The final velocity of the body
Answer:
Explanation:f=ma. S=ut+at(t)/2
s=at(t)/2 2s/t(t)=a
f=m(2s)/t(t)
f(t)(t)/2m=s
40(2)(2)/2(10)=s
160/20=s
s=8m
b.w=f(s)
40(8)=w. W=320J
KE=m(v)(v)/2
V(V)=U(u)+2aS
kE=M[(U)(u)+2as]
u=0
KE=2mas. KE=2(10)(4)(8). KE=640J
v(v)=u(u)+2as
v(v)=2(4)(8)
v(v)=64
v=8
A white ball traveling at 5.0 m/s east hits a stationary orange ball that has
the same mass. The white ball stops, and the orange ball moves away at 5.0
m/s east. What is true for this collision?
The collision is inelastic because kinetic energy is conserved.
A
B
The collision is inelastic because kinetic energy is not conserved.
C The collision is elastic because kinetic energy is conserved.
D The collision is elastic because kinetic energy is not conserved.
The kinetic energy of balls is conserved, the collision is elastic.
What is conservation of energy?Energy conservation in physics is a fundamental law of chemistry and physics stating that the total energy in an isolated system is constant despite internal changes. It is most commonly expressed as "energy can neither be created nor destroyed", and is the basis of the first law of thermodynamics.An elastic collision is one in which the system suffers no net loss of kinetic energy as a result of the collision. In an elastic collisions, both momentum and kinetic energy are conserved.When one reactant loses momentum or kinetic energy, the other reactant gains the very same amount of momentum or kinetic energy. Thereby, the total amount of kinetic momentum and energy of the system would then remain as it is, and therefore, kinetic energy is conserved.To learn more about kinetic energy refer to :
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What role does gravity play in the orbit of planets?
Answer: Gravity is what holds the planets in orbit around the sun and what keeps the moon in orbit around Earth
Explanation:
when an object is placed 12 inches from the face, how will the lens change to help focus on the object?
When an object is placed 12 inches from the face, then the lens : will thicken and therefore refract light more strongly.
How does the lens change to focus on objects that are close?The process of changing the shape of the lens to focus on near or distant objects is called accommodation. To focus on a near object , lens becomes thicker which allows the light rays to refract more strongly.
Cornea provides most of the eye's optical power or light-bending ability. When the light passes through the cornea, it is bent again for more finely adjusted focus by the crystalline lens inside the eye. Lens helps in focusing the light on the retina.
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nmr spectroscopy, or magnetic resonance spectroscopy, is a very important tool in the determination of organic structures. this technique relies on the interaction of a particular nucleus with a field followed by absorption of energy of a specific , depending on the chemical environment of the nucleus.
Nmr spectroscopy, or magnetic resonance spectroscopy, is a very important tool in the determination of organic structures.
What is NMR spectroscopy used for?
NMR spectroscopy is the use of NMR phenomena to study the physical, chemical, and biological properties of matter. Chemists use it to determine molecular identity and structure. Medical practitioners employ magnetic resonance imaging (MRI), a multidimensional NMR imaging technique, for diagnostic purposes.
How is NMR spectroscopy used in the identification of organic molecules?
Nuclear Magnetic Resonance (NMR) is an important technique to elucidate unknown organic molecules. But its sensitivity is limited and many elements lack an NMR observable isotope. So a full structure elucidation relies on several spectroscopic techniques and is normally performed by an experienced spectroscopist.
What type of radiation is used for NMR?
Like all spectroscopies, NMR uses a component of electromagnetic radiation (radio frequency waves) to promote transitions between nuclear energy levels (Resonance). Most chemists use NMR for the structure determination of small molecules.
This technique relies on the interaction of a particular nucleus with a field followed by the absorption of energy of a specific , depending on the chemical environment of the nucleus with a nuclear, magnetic field followed by absorption of energy of a specific frequency depending on the chemical environment of the nucleus.
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