why is sun the only star that can be seen during day time​

Answer:

36.5 kJ

Explanation:

Energy by machine = energy to machine × efficiency

E = 52.1 kJ × 0.70

E = 36.5 kJ

Answer:

Equal effort force

Explanation:

A class 1 lever has the support between the load and the effort hence the load tilts the plain at one end containing the support we would require an effort equal and opposite to the load to ensure movement .

Answer:

Refraction is the bending of life an example would be how when you put a straw in a glass and it looks like the straw gets detached from itself. Reflection is when light bonces off of something an example would be a mirror.

Explanation:

The way a mirror works is the light you see bounces off of the glass and gives your optical sensors the vision of what the glass reflected.

Answer:

Diffraction , refraction and reflection all are property of light that shows its wave nature.

Explanation:

When a light ray passes through a narrow single slit , the superposition of secondary wavelets produced by the same source , is called diffraction.

Example ; Single slit experiment in which the diffraction shows maxima and minima .

The banding of light due to variation in the speed of light when it travels from one medium to another is called refraction.

Example; Divergence or convergence by lenses.

The bouncing back of light from a surface is called reflection.

Example : Mirrors.

Hence all the given topics are explained.

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Answer:

0.50v

Explanation:

Now EMF is induced when there is motion of a conductor in an electric field. Michael Faraday in the annals of scientific history discovered this.

This is expressed mathematically as;

E = Magnetic field / t

but t = d/ v; d- distance, v-velocity, time

Hence E = magnetic field/ d/v

= Magnetic field× v/ d

= 0.02×30/ 1.2= 0.5

Answer:

Solar energy is a form of Electromagnetic energy

Explanation:

Solar energy is constantly flowing away from the sun and throughout the solar system. Solar energy warms the Earth, causes wind and weather, and sustains plant and animal life. The energy, heat, and light from the sun flow away in the form of electromagnetic radiation (EMR

Answer:

Power, P = 480 W

Explanation:

It is required to find the power used by 4 A appliance that is plugged into a 120 V circuit for 4 minutes. Power used by an appliance is given by the formula as follows :

[tex]P=VI[/tex]

Plugging all the values we get :

[tex]P=120\times 4\\\\P=480\ W[/tex]

So, the power used by the appliance is 480 W.

Answer:

Final velocity (v) = 36 m/s

Distance traveled (s) = 2,160 m

Explanation:

Given:

Initial velocity (u) = 0

Acceleration (a) = 0.3 m/s

Time travel (t) = 2 minutes = 120 seconds

Find:

Final velocity (v) = ?

Distance traveled (s) = ?

Computation:

v = u + at

v = 0 + 0.3(120)

v = 0.3(120)

v = 36 m/s

Final velocity (v) = 36 m/s

Distance traveled (s) = ut + (1/2)at²

Distance traveled (s) = (0.5)(0.3 × 120 × 120)

Distance traveled (s) = 2,160 m

Answer:

50 %

Explanation:

It's Fifty percent

Answer:

86605.08 N

Explanation:

The equation to calculate the force is:

Force = mass * acceleration

The force and the acceleration does not have the same direction in this case, so we need to decompose the force into its horizontal component, which is the force that will generate the horizontal acceleration:

Force_x = Force * cos(30)

Then, we have that:

Force_x = mass * acceleration

Force * cos(30) = 25000 * 3

Force * 0.866 = 75000

Force = 75000 / 0.866 = 86605.08 N

Answer:

Explanation:

Kinetic energy

Energy is defined in science as the ability to move matter or change matter in some other way.

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.

Answer:

in physics, resonance is a phenomenon in which a vibrating system or external force drives another system to oscillate with greater amplitude at specific frequencies. example a familiar example is a playground swing, which acts as a pendulum.

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Answer:

1.962 × 10⁻³ kW

Explanation:

The energy of a wave of a wave, such as an ocean wave, in regions of considerable water depth given its amplitude in a meter of crest and surface  unit is given by the relation;

[tex]E = \dfrac{\rho \times g \times A^2}{2}[/tex]

Where:

ρ = Density of water = 1000 kg/m³

g = Acceleration due to gravity = 9.81 m/s²

A = Wave amplitude = 2 cm = 0.02 m

We therefore have;

[tex]E = \dfrac{1000 \times 9.81 \times (0.02)^2}{2} = 1.962 \ \dfrac{m^2 \cdot kg}{s^2} = 1.962 \ J[/tex]

The energy is power is the energy per second which is gives;

P = E /second = 1.962 J/s = 1.962 W = 1.962 × 10⁻³ kW.

Jess wants to make her house more energy efficient. Insulating her loft, which will cost £460 and save £25 per year, is better long-term option. Therefore, option B is correct.

In order to accomplish work and to produce heat and light, energy must be transferred to a body or to a physical system. Energy is the quantitative attribute that does this. Energy is a preserved resource; according to the rule of conservation of energy, energy can only be transformed from one form to another and cannot be created or destroyed.

Computers, vehicles, communications, state-of-the-art medical technology, and many other things are all powered by energy. The demand for dependable and economical energy is especially pressing for emerging countries. It may enhance things or perhaps save lives.

A turbine generator set transforms mechanical energy into electrical energy to produce electricity. Natural gas, coal, nuclear fission, biomass, petroleum, geothermal, and solar thermal are examples of energy sources where the heat generated is used to produce steam.

Thus, option B is correct.

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Answer:

it increases the surface tension of the water

Answer:

convection

Explanation:

because in convection, molecules move with heat(i.e wind). So, when molecules move to another place, the mass will be reduce and the density will change

Answer:

C

Explanation:

Answer:

Ff = 7.35*10^5 N

Explanation:

To find the maximum transverse pulling force you use the following formula, for the friction force:

[tex]F_f=\mu N=\mu Mg[/tex] (1)

μ: friction coefficient = 0.15

N: normal force, which is equal to the weight over the wheel

M: mass of th train = 500 ton = 500 000 kg

g: gravitational acceleration = 9.8 m/s^2

You replace the values of the variables in the equation (1):

[tex]F_f=(0.15)(500000kg)(9.8m/s^2)=735000 N=7.35*10^5N[/tex]

hence, the maximum transverse pulling force is 7.35*10^5 N

Answer:

  294.524 m^3

Explanation:

The volume of a cylinder is given by the formula ...

  V = πr^2h

For a radius of 2.5 m and a length of 15 m, the volume is ...

  V = π(2.5 m)^2(15 m) = 93.75π m^3 ≈ 294.524 m^3

The volume is about 294.52 cubic meters.

Answer:

2.5 Hz

Explanation:

3.0m/s / 1.2 m=2.5 1/s=2/5 Hz

The frequency of a wave with speed of 3.0 m/s and has a wavelength of 1.2m is 2.5 Hz.

The frequency of a wave is the number of cycles per second.

Given the wavelength is 1.2 m and speed v =3.0m/s, then the frequency of the wave is

v =fλ

f = 3 / 1.2

f = 2.5 Hz

Thus, the frequency of the wave is 2.5 Hz.

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Answer:

I think it is better if you read and shortly write my explanation

Explanation:

simple pendulum with no friction, mechanical energy is conserved. Total mechanical energy is a combination of kinetic energy and gravitational potential energy. As the pendulum swings back and forth, there is a constant exchange between kinetic energy and gravitational potential energy.

Answer:

That due the the gravity anything that falls in its gravity accelerates by 25metres per second

Explanation:

Answer:

the radiation pressure that has to push the star

Explanation:

In the stars there are two forces that act in the opposite direction.

- On the one hand there is the force of gravity that the star has to collapse

- On the other is the radiation pressure that has to push the star. This pressure comes from the radiation and velocity of the particles involved in nuclear reactions.

Answer: 0.3m

Explanation:

Given the following :

Speed of radio wave(V) = 3 × 10^8 m/s

If 1M = 10^6

Frequency(F) = 90MHz = 90 × 10^6

Wavelength (λ) =?

Speed of wave (V) = frequency(F) × wavelength(λ)

V = fλ

(3 × 10^8) = (90 × 10^6) × λ

λ = (90 × 10^6) / (3 × 10^8)

λ = 30 × 10^(6 - 8)

λ = 30 × 10^-2

λ = 0.3m

Inertia is the same thing as mass, more or less. Inertia is the tendency of the object to want to stay in place if at rest, or the object's tendency to stay in motion if a force is applied to it. A train's inertia is massive because it takes a lot of force to move such a large mass, or to slow it down. This is in comparison to the other objects (rubber ball, stone, bike, and the coins).

Answer:

Inertia is the measure of the mass of the body. The greater is the mass of the body; the

greater is its inertia and vice-versa.

(a) Mass of a stone is more than the mass of a rubber ball for the same size. Hence, inertia of

the stone is greater than that of a rubber ball.

(b) Mass of a train is more than the mass of a bicycle. Hence, inertia of the train is greater

than that of the bicycle.

(c) Mass of a five rupee coin is more than that of a one-rupee coin. Hence, inertia of the five

rupee coin is greater than that of the one-rupee coin.

Answer:

Infinity = Never ending

Explanation:

The universe could be infinite, both in terms of space and time, but there is currently no way to test whether it goes on forever or is just very big. The part of the universe we are able to observe is finite, measuring about 46 billion light years in diameter.

The set of natural numbers is an infinite set. This kind of infinity is, by definition, called countable infinity. All sets that can be put into a bijective relation to the natural numbers are said to have this kind of infinity. This is also expressed by saying that the cardinal number of the set is aleph-naught (ℵ0).

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STARS ARE INFINITE , NUMBERS ARE INFINITE

Explanation:

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