Answer:
T_t = Ts (1-A √ (Rs/D)
Explanation:
The black body radiation power is given by Stefan's law
P = σ A e T⁴
This power is distributed over a spherical surface, so the intensity of the radiation is
I = P / A
Let's apply these formulas to our case. Let's start by calculating the power emitted by the Sun, which has an emissivity of one (e = 1) black body
P_s = σ A_s 1 T_s⁴
This power is distributed in a given area, the intensity that reaches the earth is
I = P_s / A
A = 4π R²
The distance from the Sun Earth is R = D
I₁ = Ps / 4π D²
I₁ = σ (π R_s²) T_s⁴ / 4π D²
I₁ = σ T_s⁴ R_s² / 4D²
Now let's calculate the power emitted by the earth
P_t = σ A_t (e) T_t⁴
I₂ = P_t / A_t
I₂ = P_t / 4π R_t²2
I₂ = σ (π R_t²) T_t⁴ / 4π R_t²2
I₂ = σ T_t⁴ / 4
The thermal equilibrium occurs when the emission of the earth is equal to the absorbed energy, the radiation affects less the reflected one is equal to the emitted radiation
I₁ - A I₁ = I₂
I₁ (1 - A) = I₂
Let's replace
σ T_s⁴ R_s²/4D² (1-A) = σ T_t⁴ / 4
T_s⁴ R_s² /D² (1-A) = T_t⁴
T_t⁴ = T_s⁴ (1-A) (Rs / D) 2
T_t = Ts (1-A √ (Rs/D)
Answer:
The velocity of the pin is opposite its acceleration on the way up.
(d) option is correct.
Explanation:
when the juggler throws a bowling pin straight in the air, the acceleration working on the pin is in the downward direction due to the gravitational force of the earth.
According to Newton's Universal Law of Gravitation
''The gravitational force is a force that attracts any objects with mass''
Answer:
C. Zero for ammeter; infinity for voltmeter
Explanation:
Ammeter: A device that is used to measure the current through a circuit.
Voltmeter: A device that is used to measure the electric potential difference between two points in a circuit.
The relation among voltage (v), current (i), and resistance (r) is given as,
In ideal cases an ammeter must have zero resistance so that there is no voltage drop across it and accurate value of current will be measured.
In case of an ideal voltmeter, the resistance should be infinite so that the current across it is zero.
Distance = (speed) x (time)
Distance = (3 x 10⁸ meter/second) x (1 hour)
Distance = 3 x 10⁸ meter-hour per second
Distance = 3 x 10⁵ kilometer-hour per second
Hmmm. That answer is perfectly correct and totally useless. We have no idea how far one meter-hour per second is. It's a unit we never use. We'd better convert the answer to a unit of length that we use every day.
(3 x 10⁵ km-hour/sec) x (3,600 sec/hour) =
(3 x 10⁵ x 3,600) (km-hour-sec/hour-sec) =
1.08 x 10⁹ km
THAT's it ! A pulse of light in vacuum travels 1.08 billion km in one hour.