Here is the energy that is left after the quantity of energy is transformed: 750 j of electrical energy is changed into 400 j of kinetic or mechanical energy, which is then turned into 0.32 j of efficient energy.
To run the fan, electrical energy is utilized.
Here, under the specified circumstances, 750 J of electrical energy is utilized to operate the fan, which is transformed into 400 J of kinetic energy. As a result, 350 J of energy is wasted due to various frictional and resistive losses.
Therefore, we may conclude that only 400 J of the 750 J available energy is used to power the fan, with the remaining energy being wasted as a result of friction.
Additionally, we can state that this fan's effectiveness will be
n = Useful ÷ Total
n = 400 ÷ 750
n = 8 ÷ 25
n = 0.32
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When a wave and/or the observer are moving, the frequency changes according to the Doppler Effect.
When the source is at rest and the observer moves away from it, the wave looks slower and its velocity will be:
v' = vsound - vobserver
In this case,
f₁ = v'/λ = (vsound - vobserver) / λ = f₀ · (<span>vsound - vobserver) / vsound
= f</span>₀ · (1 - vobserver/vsound)
On the contrary, when the source is moving away from an observer at rest, the wave appears with a different wavelengh:
λ' = (vsound + vsource) / f₀
In this case,
f₂ = v/<span>λ' = vsound / ((vsound + vsource) / f₀)
= </span>f₀ ·
Now, let's put together these two cases:
f' = v' / <span>λ' =
= </span>
<span>
= f</span>₀ ·
= f<span>₀ · </span>
<span>C) Pressure will compress a gas, reducing its volume and giving it a greater density and concentration of particles.
Let's look at the available choices and determine why or why not they're correct.
A) Pressure will expand a gas, enlarging its volume and reducing its density and concentration of particles.
* What? So increasing the pressure on a gas will make it take up a larger volume? That definitely doesn't match the world I live in. I hope that's true for you as well. Wrong choice.
B) Pressure will magnify a gas, developing its volume and multiplying its density and concentration of particles.
* Lots of interesting sounding words, but they're mostly used in a nonsense fashion. Useful if you're easily fooled by technobabble, but it's another wrong answer.
C) Pressure will compress a gas, reducing its volume and giving it a greater density and concentration of particles.
* OK. Increasing the pressure will compress a gas. So it has a smaller volume. And since it still has the same mass, the density will become greater. And the particles closer together. Everything here matches reality. Good choice.
D) Pressure will accelerate a gas, extending its volume and allowing a smaller density and concentration of particles.
* Most technobabble. Why would the gas be accelerated? No reason that I know of. Wrong choice.</span>
Answer:
Explanation:
Assuming there is only force in the y-component, the total net force acting on the parachute and the sky diver is:
(1)
Where:
is the drag force acting upwards
is the weight of the sky diver acting downwards, hence with negative sign
Then:
(2) This is the total net force excerted on the system parachute-sky diver, and the fact it is positive means is upwards
Now, according Newton's 2nd Law of Motion the force is directly proportional to the mass and to the acceleration of a body:
(3)
Where is the mass of the diver.
Substituting the known values and finding :
(4)
(5)
Finally:
This is the acceleration of the sky diver. Note it has a positive sign, which means its direction is upwards.