Air at 25ºC flows in an electric hair drier with a velocity of 6 m/s perpendicular to a Nichrome heating element. The heating el
ement is 1-mm in diameter and 36-cm long with a resistance of 1.52 Ω/m. The wire temperature cannot exceed 420ºC so that the wire will not lose strength and sag. Determine the electric current in the wire.
1 answer:
Answer:
Check the explanation
Explanation:
Electrical current can be measured according to the rate of electric charge flow in any electrical circuit:
the derivative of the electric charge by time determines the momentary current.
i(t) will be the momentary current I at time t in amps (A).
Q(t) will also be the momentary electric charge in coulombs (C).
t is the time in seconds (s).
so if the current is constant:
I = ΔQ / Δt
I will be the current in amps (A).
ΔQ will be the electric charge in coulombs (C), which is expected to flows at time duration of Δt.
Δt is the time duration in seconds (s).
Kindly check the attached image below to get the step by step explanation to the question above.
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Answer:
And replacing in the Carnot efficiency we got:
Explanation:
For this case we can use the fact that the maximum thermal efficiency for a heat engine between two temperatures are given by the Carnot efficiency:
We have on this case after convert the temperatures in kelvin this:
And replacing in the Carnot efficiency we got:
And the maximum power output on this case would be defined as:
Where represent the heat associated to the deposit with higher temperature.
Answer:
Δx = 25 ft.
Explanation:
Assuming that the person on the ground starts running at the same time as the egg is dropped, we have two simultaneous trajectories:
1 ) Egg falling:
If the egg is dropped, and we neglect the air resistance, we can use the kinematic equation that relates the distance and fall time, as follows:
yf-y₀ = 1/2* g* t²
If we take the up direction as positive, we can solve for t as follows:
0-100 ft = 1/2* (-32.15 ft/s²)* t²
⇒ t = = 2.5 sec.
2) Person on the ground running away:
In order to be able to run away, and then return to catch the egg, running at constant speed, he must run during exactly the half of the time that the egg is falling, i.e., 1.25 sec.
We can get the distance at which he can reach, applying the definition of velocity:
v = (xf-x₀) / (tfi-t₀)
If we choose t₀=0 and x₀ = 0 , we can solve for xf, as follows:
xf = v*t = 20 ft/sec*1.25 sec = 25 ft.