A roller coaster starts with a speed of 4.6 m/s at a point 49 m above the bottom of a dip.Neglecting friction, what will be the speed of the roller coaster at the top of the next
slope, which is 29 m above the bottom of the dip?

Energy is transformed and transferred in a thermodynamic system. Option B is correct

First law of thermodynamics:

It states the energy neither be created nor destroyed. It change its form from one to another. It is also known as law of conservation of energy.

It is given by the formula,

Where,

- change in internal energy

-    heat added

-    work done by the system

Since, heat is a form of energy, hence it is follow the principle of conservation of energy.

Therefore, energy is transformed and transferred in a thermodynamic system. Option B is correct

To know more about First law of thermodynamics:

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Answer:

2: A,D,E or 1,4,5

3: B

4: B

5: 12 joules

6: 53 joules

7: B,C,E or 2,3,5

8: 2,4,3,1

9: Electrical energy in the stove is transformed into heat. The heat flows to the water in the kettle, increasing the internal energy of the water. As the energy in the water increases, the water molecules move faster until the liquid water becomes water vapor. The water vapor does work on the whistle, causing it to make a sound. Energy is neither created nor destroyed, it has simply changed form in the process.

Explanation:

youre welcome

Answer:

A) α = -1.228 rev/min²

B) 7980 revolutions

C) α_t = -8.57 x 10^(-4) m/s²

D) α = 21.5 m/s²

Explanation:

A) Using first equation of motion, we have;

ω = ω_o + αt

Where,

ω_o is initial angular velocity

α is angular acceleration

t is time the flywheel take to slow down to rest.

We are given, ω_o = 140 rev/min ; t = 1.9 hours = 1.9 x 60 seconds = 114 s ; ω = 0 rev/min

Thus,

0 = 140 + 114α

α = -140/114

α = -1.228 rev/min²

B) the number of revolutions would be given by the equation of motion;

S = (ω_o)t + (1/2)αt²

S = 140(114) - (1/2)(1.228)(114)²

S ≈ 7980 revolutions

C) we want to find tangential component of the velocity with r = 40cm = 0.4m

We will need to convert the angular acceleration to rad/s²

Thus,

α = -1.228 x (2π/60²) = - 0.0021433 rad/s²

Now, formula for tangential acceleration is;

α_t = α x r

α_t = - 0.0021433 x 0.4

α_t = -8.57 x 10^(-4) m/s²

D) we are told that the angular velocity is now 70 rev/min.

Let's convert it to rad/s;

ω = 70 x (2π/60) = 7.33 rad/s

So, radial angular acceleration is;

α_r = ω²r = 7.33² x 0.4

α_r = 21.49 m/s²

Thus, magnitude of total linear acceleration is;

α = √((α_t)² + (α_r)²)

α = √((-8.57 x 10^(-4))² + (21.49)²)

α = √461.82

α = 21.5 m/s²

Answer:

50% of unpolarised light passes through the first filter because, on average, 50% of the waves are aligned with the fiter's axis.  Intensity is reduced by a factor 0.5.

The second filter then reduces the intensity by a factor cos²(θ)

Explanation:

Answer: An atom valence electron shell determines its chemical reactivity.

Explanation:

An atom's valence electron shell determines its chemical reactivity. The amount of electrons in the outermost shell of an atom is its valence electron and it determines how reactive the atom is.

The reactivity of an atom depends on the number of electrons in its outermost shell. Atoms that has their outermost electrons full e.g noble gases like argon, krypton etc are unreactive because there is no room for the atom to donate or accept any electron.

Elements like sodium and chlorine are reactive because they possesses 1 and 7 electrons in their outermost shell respectively as such they can donate and accept electrons making them reactive elements.

The valence electron shell of an atom determines its chemical reactivity. This is due to the role these outermost electrons play in the formation of chemical bonds. Atoms aim to achieve a stable state, typically with eight electrons in their outermost shell, through accepting, donating, or sharing electrons.

The correct answer to the multiple choice question about the atom's valence electron shell is '2. determines its chemical reactivity'. The outermost shell of an atom is known as the valence shell. This shell, holding the valence electrons, is essential in determining an atom's chemical reactivity. This is because it's the valence electrons that are engaged in the formation of chemical bonds.

Chemical reactivity refers to the ease with which an atom gains, loses, or shares electrons. Stable atoms, like helium or larger atoms with eight electrons, are less likely to participate in chemical reactions. They already have a filled valence shell. However, other atoms, those with less than eight electrons, will strive to complete their outer shell by interacting with other atoms, either accepting, donating or sharing electrons to achieve stability.

Importantly, not all elements have enough electrons to completely fill their outermost shells and so they form chemical bonds by sharing, accepting, or donating electrons to other atoms. The formation of these bonds is largely determined by what is often referred to as the 'octet rule', which states that atoms seek to fill or have eight electrons in their outermost electron shell to achieve greater stability.

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Answer:

You should face your fears sometimes, and get in front of a crowd do present your ideas. Not everyone is good at it, and many people get anxious when they have to speak in front of people but it’s best if you just do it and get it over with and maybe it won’t be as intimidating next time :)