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Can someone explain the law of conservation of energy?

Bad White [126]

The law of conservation of energy is:

-- Energy can't be created or destroyed.

-- Energy can't just appear out of nowhere. If you suddenly have
more energy, then the 'extra' energy had to come from somewhere.

-- Energy can't just disappear. If you suddenly have less energy,
then the 'missing' energy had to go somewhere.
________________________________________

There are also conservation laws for mass and electric charge.
They say exactly the same thing. Just write 'mass' or 'charge'
in the sentences up above, in place of the word 'energy'.
________________________________________

And now I can tell you that the conservation laws for energy and mass
are actually one single law ... the conservation of mass/energy. That's
because we discovered about 100 years ago that mass can convert
into energy, and energy can convert into mass, and it's the total of BOTH
of them that gets conserved (can't be created or destroyed).

How much mass makes how much energy ?

The answer is E = m c² .

5 0

3 years ago

A plane flies from base camp to lake a, 200 km away in the direction 20.0° north of east. after dropping off supplies it flies t

Liono4ka [1.6K]

Distance of lake a is 200 km at 20 degree north of east

distance between lake a and b is 230 km at 30 degree west of north

now the distance between base and lake b is given as

$d = d_1 + d_2$

given that

$d_1 = 200 cos20 i + 200 sin20 j$

$d_1 = 187.94 i + 68.4 j$

$d_2 = -230 sin30 i + 230 cos30 j$

$d_2 = -115 i + 199.2 j$

now the total distance is

$d = (187.94 - 115)i + (199.2 + 68.4)j$

$d = 72.94 i + 267.6 j$

now the magnitude of the distance is given as

$d = \sqrt{72.94^2 + 267.6^2}$

$d = 277.4$

also the direction is given as

$\theta = tan^{-1}\frac{267.6}{72.94}$

$\theta = 74.7 degree$

<em>so it is 277.4 km at 74.7 degree North of East</em>

8 0

3 years ago

Which ground rule for group work was broken in the following scenario?

SpyIntel [72]

Answer:

йцу21241

Explanation:

ere taking their seats. Finn and Jan presented the progress they had made on the project since the last meeting. Everyone engaged in the subsequent discussions, asking questions and offering ideas.

5 0

2 years ago

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A trained eye in the dark for an extended period of time may pick up a light stimulus from a light source, at the lowest radiate

frez [133]

Answer:

#_photons = 30 photons / s

Explanation:

Let's start by finding the energy of a photon of light, let's use the Planck relation

E = h f

the speed of light is related to wavelength and frequency

c = λ f

we substitute

E = h c /λ

E₀ = 6.63 10⁻³⁴ 3 10⁸/500 10⁻⁹

E₀ = 3.978 10⁻¹⁹ J

now let's use a direct proportion rule. If the energy of a photon is Eo, how many fornes has an energy E = 1.2 10⁻¹⁷ J in a second

#_photons = 1 photon (E / Eo)

#_photons = 1 1.2 10⁻¹⁷ /3.978 10⁻¹⁹

#_photons = 3.0 10¹

#_photons = 30 photons / s

3 0

2 years ago

Which of the following are inertial reference frames? A. A car driving at steady speed on a straight and level road. B. A car dr

Aloiza [94]

Answers:

A. A car driving at steady speed on a straight and level road.

B. A car driving at steady speed up a 10∘ incline.

Explanation:

An object is said to be in an inertial reference frame if the net force acting on the object is zero. According to Newton's second law, this also means that the acceleration of the object is also zero:

$F=ma$

Since F=0, a=0 as well.

Let's now analyze each case.

A. A car driving at steady speed on a straight and level road. --> YES: this is an inertial reference frame, because the car is keeping a constant speed and a constant direction, so its velocity is not changing, and its acceleration is zero.

B. A car driving at steady speed up a 10∘ incline. --> YES: this is an inertial reference frame, because the car is keeping a constant speed and a constant direction, so its velocity is not changing, and its acceleration is zero.

C. A car speeding up after leaving a stop sign. --> NO: this is not an intertial reference frame, because the car is speeding up, so it is accelerating.

D. A car driving at steady speed around a curve. --> NO: this is not an inertial reference frame, because the car is changing direction, therefore its velocity is changing and so the car is accelerating.

So the only two choices which are correct are A and B.

8 0

3 years ago

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