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UkoKoshka [18]
3 years ago
12

You set out to design a car that uses the energy stored in a flywheel consisting of a uniform 80-kg cylinder of radius r that ha

s a maximum angular speed of 430 rev/s. the flywheel must deliver an average of 2.00 kj of energy for each kilometer of distance. find the smallest value of r for which the car can travel 300 km without the flywheel needing to be recharged.
Physics
1 answer:
Oliga [24]3 years ago
8 0
E = 300km * 2000J/km = 600000J

The rotational energy is given by:
E = 0.5 * I * ω² 

I for a uniform cylinder is given by:
I  = 0.5 * m * r²

Resulting equation:
E = 0.25 * m * r² * ω²

Given values:
ω = 430 rev/s = 430 * 2π / s
E = 600000

Solve for r.
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9. A wave on Beaver Dam Lake passes by two docks that are 40.0 m apart.
Kobotan [32]

Answers:

a) 10 m

b) time=1.6 s, frquency=0.625 Hz

c) 6.25 m/s

Explanation:

a) If there is a crest at each dock and another three crests between the two docks, and the wavelength \lambda is the distance between to crests; this means we have 4\lambda in 40 m:

40 m=4\lambda

Clearing \lambda:

\lambda=\frac{40 m}{4}

\lambda=10 m

b) This part can be solved by a Rule of Three:

If 10 waves ---- 16 s

1 wave ----- T

Then:

T=\frac{(1 wave)(16 s)}{10 waves}

T=1.6 s This is the period of the wave

On the other hand, the frequency f of the wave has an inverse relation with its period T:

f=\frac{1}{T}

f=\frac{1}{1.6 s}

f=0.625 Hz This is the frequency of the wave

c) The speed v of a wave is given by the following equation:

v=\frac{\lambda}{T}

v=\frac{10 m}{1.6 s}

Finally:

v=6.25 m/s

4 0
3 years ago
A rock rolls down a hill. Which form of energy is this an example of? (2 points)
Bond [772]

Answer:

c.Mechanical

Explanation:

6 0
3 years ago
What is the potential difference across a parallel-plate capacitor whose plates are separated by a distance of 4.0 mm where each
suter [353]

The potential difference across the parallel plate capacitor is 2.26 millivolts

<h3>Capacitance of a parallel plate capacitor</h3>

The capacitance of the parallel plate capacitor is given by C = ε₀A/d where

  • ε₀ = permittivity of free space = 8.854 × 10⁻¹² F/m,
  • A = area of plates and
  • d = distance between plates = 4.0 mm = 4.0 × 10⁻³ m.

<h3>Charge on plates</h3>

Also, the surface charge on the capacitor Q = σA where

  • σ = charge density = 5.0 pC/m² = 5.0 × 10⁻¹² C/m² and
  • a = area of plates.

<h3>The potential difference across the parallel plate capacitor</h3>

The potential difference across the parallel plate capacitor is V = Q/C

= σA ÷ ε₀A/d

= σd/ε₀

Substituting the values of the variables into the equation, we have

V = σd/ε₀

V = 5.0 × 10⁻¹² C/m² × 4.0 × 10⁻³ m/8.854 × 10⁻¹² F/m

V = 20.0 C/m × 10⁻³/8.854 F/m

V = 2.26 × 10⁻³ Volts

V = 2.26 millivolts

So, the potential difference across the parallel plate capacitor is 2.26 millivolts

Learn more about potential difference across parallel plate capacitor here:

brainly.com/question/12993474

7 0
3 years ago
A planet moves forward because of momentum <br><br> True or False??
lorasvet [3.4K]

Answer:

true

Explanation:

8 0
3 years ago
Rock X is released from rest at the top of a cliff that is on Earth. A short time later, Rock Y is released from rest from the s
frosja888 [35]

Answer:

C) True. S increases with time, v₁ = gt and v₂ = g (t-t₀)  we see that for the same t v₁> v₂

Explanation:

You have several statements and we must select which ones are correct. The best way to do this is to raise the problem.

Let's use the vertical launch equation. The positive sign because they indicate that the felt downward is taken as an opponent.

Stone 1

    y₁ = v₀₁ t + ½ g t²

    y₁ = 0 + ½ g t²

Rock2

It comes out a little later, let's say a second later, we can use the same stopwatch

     t ’= (t-t₀)

    y₂ = v₀₂ t ’+ ½ g t’²

    y₂ = 0 + ½ g (t-t₀)²

    y₂ = + ½ g (t-t₀)²

Let's calculate the distance between the two rocks, it should be clear that this equation is valid only for t> = to

    S = y₁ -y₂

    S = ½ g t²– ½ g (t-t₀)²

    S = ½ g [t² - (t²- 2 t to + to²)]  

    S = ½ g (2 t t₀ - t₀²)

    S = ½ g t₀ (2 t -t₀)

This is the separation of the two bodies as time passes, the amount outside the Parentheses is constant.

For t <to.  The rock y has not left and the distance increases

For t> = to.  the ratio (2t/to-1)> 1 therefore the distance increases as time

passes

Now we can analyze the different statements

A) false. The difference in height increases over time

B) False S increases

C) Certain s increases with time, v₁ = gt and V₂ = g (t-t₀) we see that for the same t   v₁> v₂

3 0
4 years ago
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