Answer:
a). kJ/kg
b). kJ/kg-K
Explanation:
a). The energy rate balance equation in the control volume is given by
kJ/kg
b). Entropy produced from the entropy balance equation in a control volume is given by
kJ/kg-K
Answer:
A. The electron releases energy in form of light
Explanation:
This emission is known as spontaneous emission.
Answer:
I = 21.13 mA ≈ 21 mA
Explanation:
If
I₁ = 5 mA
L₁ = L₂ = L
V₁ = V₂ = V
ρ₁ = 1.68*10⁻⁸ Ohm-m
ρ₂ = 1.59*10⁻⁸ Ohm-m
D₁ = D
D₂ = 2D
S₁ = 0.25*π*D²
S₂ = 0.25*π*(2*D)² = π*D²
If we apply the equation
R = ρ*L / S
where (using Ohm's Law):
R = V / I
we have
V / I = ρ*L / S
If V and L are the same
V / L = ρ*I / S
then
(V / L)₁ = (V / L)₂ ⇒ ρ₁*I₁ / S₁ = ρ₂*I₂ / S₂
If
S₁ = 0.25*π*D² and
S₂ = 0.25*π*(2*D)² = π*D²
we have
ρ₁*I₁ / (0.25*π*D²) = ρ₂*I₂ / (π*D²)
⇒ I₂ = 4*ρ₁*I₁ / ρ₂
⇒ I₂ = 4*1.68*10⁻⁸ Ohm-m*5 mA / 1.59*10⁻⁸ Ohm-m
⇒ I₂ = 21.13 mA
Answer:
10 m/s
Explanation:
Given:
Amplitude of atomic vibrations (λ) = 10⁻⁹ cm = 10⁻⁹ × 10⁻² m = 10⁻¹¹ m [1 cm = 10⁻² m]
Frequency of the vibrations (f) = 10¹² Hz
In order to find the atom's maximum speed, we need to make use of the formula that relates speed, frequency and wavelength of the vibration.
Therefore, the formula for maximum speed is given as:
Now, plug in the values given and solve for speed 'v'. This gives,
Therefore, the atom's maximum speed due to thermal energy provided is 10 m/s.
Answer:
(a). 19.0 m/s
(b). 9.5m/s
Explanation:
Assuming speed of sound is 343m/s.
(a).
As the train approaches, from the the Doppler equation we have
solving for we get:
.
And as the train cuts its speed in half, the equation gives
substituting the value of we get:
or 68.6 km per hour, which is the speed of the train before slowing down.
(b).
The speed of the train after slowing down is half the previous speed; therefore,
or 34.3 km per hour.