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Novosadov [1.4K]
3 years ago
13

The minimum frequency of light needed to eject electrons from a metal is called the threshold frequency, ????0 . Find the minimu

m energy needed to eject electrons from a metal with a threshold frequency of 4.17×1014 s−1. E0= J With what maximum kinetic energy will electrons be ejected when this metal is exposed to light with a wavelength of 245 nm? KEelectron= J
Physics
1 answer:
Reptile [31]3 years ago
4 0

Answer:

Explanation:

Threshold frequency = 4.17 x 10¹⁴ Hz .

minimum energy required = hν where h is plank's constant and ν is frequency .

E = 6.6 x 10⁻³⁴ x 4.17 x 10¹⁴

= 27.52 x 10⁻²⁰ J .

wavelength of radiation falling = 245 x 10⁻⁹ m

Energy of this radiation = hc / λ

c is velocity of light and  λ  is wavelength of radiation .

= 6.6 x 10⁻³⁴ x 3 x 10⁸ / 245 x 10⁻⁹

= .08081 x 10⁻¹⁷ J

= 80.81 x 10⁻²⁰ J

kinetic energy of electrons ejected = energy of falling radiation - threshold energy

= 80.81 x 10⁻²⁰  - 27.52 x 10⁻²⁰

= 53.29 x 10⁻²⁰ J .

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elena-s [515]

Answer:

The speed after being pulled is 2.4123m/s

Explanation:

The work realize by the tension and the friction is equal to the change in the kinetic energy, so:

W_T+W_F=K_f-K_i (1)

Where:

W_T=T*x*cos(0)=32N*3.2m*cos(30)=88.6810J\\W_F=F_r*x*cos(180)=-0.190*mg*x =-0.190*10kg*9.8m/s^{2}*3.2m=59.584J\\ K_i=0\\K_f=\frac{1}{2}*m*v_f^{2}=5v_f^{2}

Because the work made by any force is equal to the multiplication of the force, the displacement and the cosine of the angle between them.

Additionally, the kinetic energy is equal to \frac{1}{2}mv^{2}, so if the initial velocity v_i is equal to zero, the initial kinetic energy K_i is equal to zero.

Then, replacing the values on the equation and solving for v_f, we get:

W_T+W_F=K_f-K_i\\88.6810-59.5840=5v_f^{2}\\29.097=5v_f^{2}

\frac{29.097}{5}=v_f^{2}\\\sqrt{5.8194}=v_f\\2.4123=v_f

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8 0
3 years ago
If the mass of a 1.8 g paperclip was able to be completely converted to energy, how much energy would you obtain?
Anton [14]

Answer:

E=1.62\times 10^{14}\ J

Explanation:

Given that,

The mass of the paperclip, m = 1.8 g = 0.0018 kg

We need to find the energy obtained. The relation between mass and energy is given by :

E=mc^2

Where

c is the speed of light

So,

E=0.0018\times (3\times 10^8)^2\\\\E=1.62\times 10^{14}\ J

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3 years ago
Two blocks, A and B, are connected by a rope. A second rope is connected to block B and a steady, horizontal tension force of T
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Answer:

40 N

Explanation:

We are given that

Speed of system is constant

Therefore, acceleration=a=0

Tension applied on block B=T=50 N

Friction force=f=10 N

We have to find the friction force acting on block A.

Let T' be the tension in string connecting block A and block B and friction force on block A be f'.

For Block B

T-f-T'=m_Ba

Where m_B=Mass of block B

Substitute the values

50-10-T'=m_B\times 0=0

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For block A

T'-f'=m_Aa

Where m_A=Mass of block A

Substitute the values

40-f'=m_A\times 0=0

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3 0
3 years ago
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LuckyWell [14K]

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Explanation :

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Thus, the expression for final pressure in the two containers will be:

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P=\frac{P_1V_1+P_2V_2}{V}

where,

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V_1 = volume of N₂ gas = 3.00 L

V_2 = volume of Ar gas = 2.00 L

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V = final volume of gas = (4.45 + 2.75) L = 7.2 L

Now put all the given values in the above equation, we get:

P=\frac{(4.45atm)\times (3.00L)+(2.75atm)\times (2.00L)}{7.2L}

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