Answer:
λ = 4.1638 10⁻⁷ m
Explanation:
The photoelectric effect was explained by Einstein assuming that the radiation acts like particles and the equation that describes the process is
K = h f -Ф
where K is the kinetic energy of the emitted electrons, hf the energy of the photons according to Planck's equation and Ф the work function of the material
In this case they give us the kinetic energy of the electrons
K = 0.7 eV
The sodium work function is tabulated Ф = 2.28 eV
Let's find the frequency of the photons
f = (K + Ф) / h
Planck's constant is
h = 6.626 10⁻³⁴ J s (1 eV / 1.6 10⁻¹⁹ J) = 4.136 10⁻¹⁵ eV s
f = (0.7 + 2.28) / 4.136 10⁻¹⁵
f = 7.2050 10¹⁴ Hz
let's find the wavelength using the relationship between speed and frequency and wavelength
c = λ f
λ = c / f
λ = 3 10⁸ / 7.205 10¹⁴
λ = 4.1638 10⁻⁷ m
Answer:
a) a = 19.0 m/s²
b) a = 2.9 m/s²
Explanation:
a) We draw the free body diagram of the box. There are 4 forces: the normal force N, the weight mg, the constant force F and the kinetic frictional force μ_kN. We can take the coordinate system which is rotated 55° from the horizontal, to ease the calculations. So, we write the equations of motion in each axis:
Substituting the expression for N in the first equation, we have:
If we plug in the given values, we have:
Since we chose the right-downward direction as positive, the positive sign in this case means that the box is accelerated downwards above the ramp.
b) In this case, the constant force F and the kinetic frictional force μ_kN point to the opposite side. In other words, we can just only change the sign of this two forces in the equations of part (a) and obtain:
Plugging in the given values:
Since we chose the right-downward direction as positive, the negative sign in this case means that the box is accelerated upwards above the ramp.
This means that the magnitude of the acceleration in this case is 2.9m/s².
Answer:
idk man
Explanation:
i am suffereing from this i am in Mr.GoofFreinds class and this quiz is hard.
Of my knowlaedge, the suns light rays are so intense that they bounce off of other planets and shine on the face of the moon giving us the ability ti see the moon at night.