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Vedmedyk [2.9K]
3 years ago
15

man stands on a platform that is rotating (without friction) with an angular speed of 1.2 rev/s; his arms are outstretched and h

e holds a brick in each hand.The rotational inertia of the system consisting of the man, bricks, and platform about the central vertical axis of the platform is 6.0 k g times m squared. If by moving the bricks the man decreases the rotational inertia of the system to 2.0 k g times m squared, what is the resulting angular speed of the platform in rad/s? Express to 3 sig figs.
Physics
1 answer:
-Dominant- [34]3 years ago
3 0

Answer:

w₂ = 22.6 rad/s

Explanation:

This exercise the system is formed by platform, man and bricks; For this system, when the bricks are released, the forces are internal, so the kinetic moment is conserved.

Let's write the moment two moments

initial instant. Before releasing bricks

       L₀ = I₁ w₁

final moment. After releasing the bricks

       L_{f} = I₂W₂

       L₀ = L_{f}

       I₁ w₁ = I₂ w₂

       w₂ = I₁ / I₂ w₁

let's reduce the data to the SI system

     w₁ = 1.2 rev / s (2π rad / 1rev) = 7.54 rad / s

 

 let's calculate

       w₂ = 6.0/2.0   7.54

       w₂ = 22.6 rad/s

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Explanation:

The given data is as follows.

         mass (m) = 170 kg,        Distance (s) = 9.6 m

        Height (h) = 3.3 m,         Force (F) = 1400 N

First, we will calculate the work performed by her as follows.

                W = Fs

                    = 1400 N \times 9.6 m

                    = 13440 J

Hence, minimal work necessary to lift the refrigerator is as follows.

               U = mgh

                   = 170 kg \times 9.8 \times 3.3 m

                   = 5497.8 J

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7 0
3 years ago
We want to construct a solenoid with a resistance of 4.30 Ω and generate a magnetic field of 3.70 × 10−2 T at its center when ap
marshall27 [118]

Answer with Explanation:

We are given that

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Magnetic field,B=3.7\times 10^{-2} T

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Radius of wire,r=\frac{d}{2}=\frac{0.5\times 10^{-3}}{2}=0.25\times 10^{-3} m

1mm=10^{-3} m

Radius of solenoid,r'=1 cm=1\times 10^{-2} m

1 cm=10^{-2} m

Resistivity of copper,\rho=1.68\times 10^{-8}\Omega m

We know that

R=\frac{\rho l}{A}

Where A=\pi r^2

Using the formula

4.3=\frac{1.68\times 10^{-8}\times l}{\pi(0.25\times 10^{-3})^2}

l=\frac{4.3\times \pi(0.25\times 10^{-3})^2}{1.68\times 10^{-8}}=50.23 m

Number of turns of wire=\frac{l}{2\pi r'}

Number of turns of wire=\frac{50.26}{2\pi(1\times 10^{-2}}=800

Hence, the number of turns of the  solenoid,N=799

Magnetic field in solenoid,B=\mu_0 nI

3.7\times 10^{-2}=4\pi\times 10^{-7} n\times 4.6

n=\frac{3.7\times 10^{-2}}{4\times 3.14\times 10^{-7}\times 4.6}

n=6404 turns/m

n=\frac{N}{L}

L=\frac{N}{n}

L=\frac{799}{6404}

L=0.125 m=0.125\times 100=12.5 cm

Length of solenoid=12.5 cm

1m=100 cm

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Answer:

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¨Drivers who are talking on the phone, even on a hands-free device, are up to four times more likely to be involved in a crash.¨

I hope this helps! Have a great day!

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Which example is NOT a part of the electromagnetic spectrum?
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Electricity is NOT a part of electromagnetic spectrum.

An electromagnetic spectrum contains electromagnetic radiations arranged according to frequencies and wavelength.

<h2>Further Explanation </h2><h3>Electromagnetic waves  </h3>
  • Electromagnetic waves are types of waves that do not require a material medium for transmission.
  • These waves are mostly transverse in nature, which means the direction of transmission is perpendicular to the direction of vibration of particles.
  • They include, light waves, radio waves, x-rays, infra-red, etc.
<h3>Electromagnetic spectrum </h3>
  • An electromagnetic wave shows electromagnetic waves arranged according to frequencies and wavelength.  
  • Electromagnetic spectrum contains electromagnetic waves: Gamma rays, x-rays, Ultraviolet, Visible light, infra-red, microwaves, and radio waves.
  • The electromagnetic spectrum is divided into various sections based on wavelength, with gamma rays having the shortest wavelength and radio waves having the longest wavelength.
  • The part of the electromagnetic spectrum that we can see using our naked eyes is called the visible light spectrum.
  • In order of frequency, the radio waves have the lowest frequency while gamma rays have the largest frequency.
<h3>General characteristics of electromagnetic waves  </h3>
  • They travel with the speed of light (3.0 x 10^8 m/s)
  • They possess energy that is given by; E =hf, where h is the plank’s constant and f is the frequency.
  • They are transverse in nature, and therefore, the wavelength is measured between successful crests or troughs.
  • They can travel through vacuum

Keywords: Electromagnetic spectrum, electromagnetic waves.

<h3>Learn more about:  </h3>
  • Electromagnetic spectrum: brainly.com/question/11725209
  • Electromagnetic waves: brainly.com/question/12450147
  • Characteristics of electromagnetic waves: brainly.com/question/12450147

Level: High school  

Subject: Physics

Topic: Electromagnetic spectrum

8 0
3 years ago
Read 2 more answers
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