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Vesnalui [34]
3 years ago
9

An 80 kg skier stands at the top of a 40-meter slope. She then skis down the slope. What is her approximate speed at the bottom

of the slope if friction is negligible and her kinetic energy is 31360 J?
Physics
1 answer:
irinina [24]3 years ago
5 0

Thank you for that information.  If we know her mass and kinetic energy, then we don't need any of that other business about the height of the slope, her skiing ability, the friction of the snow, what she uses to wax her skis, the color of her parka, or what she had for lunch at the chalet.  The mass and kinetic energy are enough to answer the question.

Kinetic Energy = (1/2) · (mass) · (speed)²

31,360 J = (1/2) · (80 kg) · (speed)²

speed² = (31,360 J) / (40 kg)

speed² = 784 m²/s²

speed = <em>28 m/s</em>

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What is the relationship between wavelength of light and the quantity of energy per photon?
slamgirl [31]

Answer:

The quantity of energy per photon is inversely proportional to the wavelength of the light.

Explanation:

Energy of light is given as

E = hf

where E = energy of the photons,

f = frequency of the light

If the number of photons = n

(E/n) = (h/n) f

Let (E/n) = E'

(h/n) = h'

But the frequency of light is related to wavelength through the relation

v = fλ

where v = speed of light = c

λ = wavelength of light

f = (c/λ)

E' = h' f

Substituting for f

E' = h' (c/λ)

h' and c are both constants, h'×c = K

E' = (K/λ)

So, the quantity of energy per photon is inversely proportional to the wavelength of the light.

Hope this Helps!!!

3 0
4 years ago
Read 2 more answers
Two electrons are at rest and separated by a distance of 4.32 × 10-10 m. When they are released they accelerate away from each o
sasho [114]

Answer:

Speed of electron when their separation increased by a factor of 4.10 is 9.41 x 10⁵ m/s .

Explanation:

The electric potential energy is given by the relation :

U = \frac{kq_{1}q_{2}  }{r}

Here q₁ and q₂ are the two charge particles and r is the distance between them and k is electric constant.

In this case, there are two electrons which are separated by the distance 4.32 x 10⁻¹⁰ m.

Let e be the electron charge and r₁ be the distance between them. Then, the initial electric potential energy is :

U_{1}  = \frac{ke^{2}   }{r_{1} }

Now, the distance between the electrons increases by the factor of 4.10. Let r₂ be the new distance between them i.e. r₂ = 4.10 r₁.

Thus, the new electric potential energy is :

U_{2}  = \frac{ke^{2}   }{r_{2} }=\frac{ke^{2}   }{4.10r_{1} }

Applying law of conservation of energy :

ΔU  = ΔK

Here ΔU is change in electric potential energy and ΔK is change in kinetic energy.

( U₁  - U₂ ) = ( K₂ - K₁ )

Here K₂ and K₁ are initial and final kinetic energy of electron.

Since, the electron initially is at rest, so its initial kinetic energy is zero. Thus, the above equation becomes:

K₂ = U₁ - U₂

\frac{1}{2}mv^{2}=\frac{ke^{2}   }{r_{1} }- \frac{ke^{2}   }{4.10r_{1} }

Here m and v are the mass and final speed of electron respectively.

v^{2}=\frac{2}{m} \frac{ke^{2}   }{r_{1} }(1- \frac{1  }{4.10 })

Substitute 9.1 x 10⁻³¹ kg for m, 9 x 10⁹ N m² C⁻² for k, 1.6 x 10⁻¹⁹ C for e and 4.32 x 10⁻¹⁰ m for r₁ in the above equation.

v^{2}=\frac{2}{9.1\times10^{-31} } \frac{9\times10^{9}\times(1.6\times10^{-19})^{2}   }{4.32\times10^{-10} }(1- \frac{1  }{4.10 })

v^{2}=8.86\times10^{11}

v = 9.41 x 10⁵ m/s

5 0
3 years ago
Just wondering if I did this right
Kisachek [45]

Yeah

All they are all correct

5 0
3 years ago
What causes the electric charges to flow from one end of the battery to the other? a balance in electric potential a balance in
Vilka [71]
I think the correct answer from the choices listed above is the third option. It is the difference in electrical potential that causes the electric charges to flow from one end of the battery to the other. Hope this answers the question. Have a nice day.
8 0
4 years ago
Read 2 more answers
A 1800kg car has a velocity of 30 m/s to the east what is the momentum of the car <br> p=m(v)
Anastasy [175]

Answer:

54000 kg*m/s

Explanation:

1800*30= 54000

8 0
2 years ago
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