Explanation:
Distance covered by the particle is given by:
Distance (d) = rate (v) × time (t)
Speed of Mary, v₁ = 50 mph
Speed of Jim, v₂ = 60 mph
It is assumed that, Mary and Jim leave at the same time. After one hour, Jim is 10 miles ahead.
Distance travelled by Jim, d₁ = (60t + 10)
Distance travelled by Mary, d₂ = 50t
The distance between Mary and Jim is greater than or equal to 100 miles.
So, Jim takes is 9 hours more than Mary to cover same distance. Hence, this is the required solution.
Answer:
Ф = 2.179 eV
Explanation:
This exercise has electrons ejected from a metal, which is why it is an exercise on the photoelectric effect, which is explained assuming the existence of energy quanta called photons that behave like particles.
E = K + Ф
the energy of the photons is given by the Planck relation
E = h f
we substitute
h f = K + Ф
Ф= hf - K
the speed of light is related to wavelength and frequency
c = λ f
f = c /λ
Φ =
let's reduce the energy to the SI system
K = 0.890 eV (1.6 10⁻¹⁹ J / 1eV) = 1.424 10⁻¹⁹ J
calculate
Ф = 6.63 10⁻³⁴ 3 10⁸/405 10⁻⁹ -1.424 10⁻¹⁹
Ф = 4.911 10⁻¹⁹ - 1.424 10⁻¹⁹
Ф = 3.4571 10⁻¹⁹ J
we reduce to eV
Ф = 3.4871 10⁻¹⁹ J (1 eV / 1.6 10⁻¹⁹ J)
Ф = 2.179 eV