If a surface looks "shiny" to you, that's because it reflects all
or most of the visible light that hits it. That doesn't always mean
that the same surface reflects other, non-visible wavelengths of
light. Infrared radiation may also reflect off of it, and probably
does. But you can't be sure just because it's visibly shiny.
molecules of water are never destroyed - they go through various uses in a cycle of re-use. beginning in the ocean. a water molecue is attached to the wet suit of a deep sea diver. when the diver gets back on his boat, the water molecule leaves the ocean. Diver dry his suit under the sun. The water molecule is evaporated to the air. It meets up with more water molecules to form cloud. Cloud becomes rain over ground. Rain drains into stream which merges into river. River runs out to the ocean and the water cycle starts anew.
The resistance expected of the heater is 50.1 ohms.
<h3>What is resistance?</h3>
Resistance can be defined as the opposition to the flow of electric current in an electric circuit. The S.I unit of resistance is Ohms (Ω).
To calculate the resistance of the heater, we use the formula below.
<h3>Formula:</h3>
- R = V²/P............. Equation 1
Where:
- R = Resistance of the heater
- P = Power of the heater
- V = Voltage supplied to the heater
From the question,
Given:
- V = 480 V
- P = 4.6 kW = 4600 W
Substitute these values into equation 1
- R = (480²)/4600
- R = 50.1 ohms.
Hence, the resistance expected of the heater is 50.1 ohms.
Learn more about resistance here: brainly.com/question/17563681
Answer:
Explanation:
a ) Entropy change dS = dQ/T
= mcdT /T
Integrating both sides
S₂ - S₁ = - mclnT₂ /T₁
= - .5 X 4200 ln (85+273) /( 20 + 273 )
.5 X 4200 ln 358/ 293
= - 417.6 J/K
Entropy change will be negative as heat is lost by the system .
b ) Sine there is no change in the temperature of air , This heat will enter air at temperature ( 20+ 273) K = 293 K
Heat entering air
= .5 x 4200 x 65
= 136500 J
Change in entropy
136500 / 293 ( room temperature is constant at 293k
= + 465.87 J/K
Entropy change will be positive as heat is gained by the system .
Total change in the entropy of the system (tea + air )
= +465.87 - 417.6
= 48.27 J/K
Entropy change will be negative as heat is lost by the system .
The temperature change in water is 9.95°. The temperature change in methanol is 20.65°. Water removes the thermal energy from the engine better.
<h3>What is a cooling system?</h3>
A cooling system is a system that is design to reduce the temperature of a car engine as the car in in operation.
For water;
H = mcθ
H = heat added
m = mass of water
c = heat capacity of water
θ = temperature rise
θ = H/mc
θ = 836.0 × 10^3 J/20 Kg × 4200
θ = 9.95°
For methanol;
mass = density × volume = 0.80 g/cm3 × 20000cm^3 = 16Kg
Hence;
θ = 836.0 × 10^3 J/16Kg × 2530J
θ = 20.65°
The thermal energy that is removed is higher with water.
Learn more about specific heat capacity:brainly.com/question/2530523
