Answer:
speed are different at different places
Explanation:
because it's top speed is 50km/h,so it's initial speed may be less. when it covers some distance it's speed changes again. then we have given a mean speed .mean speed means sum of all speed divided by sum of total time.so the mean speed and final speed differs from each other
Answer:
The work function ϕ of the metal = 53.4196 x 10⁻¹⁶ J
Explanation:
When light is incident on a photoelectric material like metal, photoelectrons are emitted from the surface of the metal. This process is called photoelectric effect.
The relationship between the maximum kinetic energy (
) of the photoelectrons to the frequency of the absorbed photons (f) and the threshold frequency (f₀) of the photoemissive metal surface is:
= h(f − f₀)
= hf - hf₀
E is the energy of the absorbed photons: E = hf
ϕ is the work function of the surface: ϕ = hf₀
= E - ϕ
Frequency f = 8.12×10¹⁸ Hz
Maximum kinetic energy
= 4.16×10⁻¹⁷ J
Speed of light c = 3 x 10⁸ m/s
Planck's constant h = 6.63 × 10⁻³⁴ Js
E = hf = 6.63 × 10⁻³⁴ x 8.12×10¹⁸
E = 53.8356 x 10⁻¹⁶ J
from
= E - ϕ ;
ϕ = E - 
ϕ = 53.8356 x 10⁻¹⁶ - 4.16×10⁻¹⁷
ϕ = 53.4196 x 10⁻¹⁶ J
The work function of the metal ϕ = 53.4196 x 10⁻¹⁶ J
Answer:
The gravitational force between them quadruples
Explanation:
According to law of gravitation, the force of attraction (F) between two masses m1 and m2 is directly proportional to the product of the masses and inversely proportional to the square of the distance(r) between them. Mathematically,
F1 = Gm1m2/r²... 1
If their masses doubles, the formula becomes;
F2 = G(2m1)(2m2)/r²
F2 = 4Gm1m2/r² ... 2
Dividing equation 2 by 1, we have;
F2/F1 = {4Gm1m2/r²}÷{Gm1m2/r²}
F2/F1 = 4Gm1m2/r²×r²/Gm1m2
F2/F1 = 4
F2 = 4F1
The gravitational force between the masses when they doubles quadruples.
Li2O is the molecular formula for lithium oxide.
To solve this problem it is necessary to express the term of the wavelength of continuous x-rays according to the Planck constant, the speed of light, the charge of the electron and the voltage. This definition is expressed mathematically as

Here,
h is Planck's constant
c is speed of light
e is charge of electron
V is the potential to which the electrons are accelerated.
From this definition we can see that the wavelength is independent of the mass of the target material. Therefore the wavelength will remain the same.