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yawa3891 [41]
3 years ago
11

What metal is used to make soft magnets?

Physics
1 answer:
Lubov Fominskaja [6]3 years ago
5 0

Answer:

iron

Explanation:

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An 8-hour exposure to a sound intensity level of 90.0 dB may cause hearing damage. What energy in joules falls on a 0.800-cm-dia
11111nata11111 [884]

Answer:

1.4E-3J

Explanation:

Given that

Time = 8hrs = 28.8E3 seconds

Intensity= 90dB

D= 0.008m

Radius= 0.004m

So intensity is sound level Bis

10dBlog(I/Io)

I= 10 (B/10dB)Io

= 10( 90/10) x 10^-12

=0.001W/m²

But we know that

I = P/A

P= I πr²

= 5.02 x10^-8W

But energy is power x time

So E= 5.02E-8 x 28.8E3

= 1.4E-3J

5 0
3 years ago
Read 2 more answers
Calculated the measurement uncertainty for Kinetic Energy when :mass = 1.3[kg] +/- 0.4[kg]velocity= 5.2 [m/s] +/- 0.2 [m/s]KE= 1
andriy [413]

Answer:

\rm KE\pm \Delta KE = 17.6\pm 6.8\ J.

Explanation:

<u>Given:</u>

  • Mass, \rm m\pm\Delta m = 1.3\pm 0.4\ kg.
  • Velocity, \rm v\pm \Delta v = 5.2\pm 0.2\ m/s.

where,

\rm \Delta m,\ \Delta v are the uncertainties in mass and velocity respectively.

The kinetic energy is given by

\rm KE = \dfrac 12 mv^2 = \dfrac 12 \times 1.3\times 5.2^2=17.576\approx 17.6\ J.

The uncertainty in kinetic energy is given as:

\rm \dfrac{\Delta KE}{KE}=\dfrac{\Delta m}{m}+\dfrac{2\Delta v}{v}\\\dfrac{\Delta KE}{17.6}=\dfrac{0.4}{1.3}+\dfrac{2\times 0.2}{5.2}\\\dfrac{\Delta KE}{17.6}=0.384\\\Rightarrow \Delta KE = 17.6\times 0.384 = 6.7854\ J\approx6.8\ J\\\\Thus,\\\\KE\pm \Delta KE = 17.6\pm 6.8\ J.

7 0
3 years ago
For thermal equilibrium at temperature Tan appropriate measure of energy is kT where k is Boltzmann's constant. Convert the foll
Schach [20]

Answer:

1 cm⁻¹ =1.44K  1 ev = 1.16 10⁴ K

Explanation:

The relationship between temperature and thermal energy is

     E = K T

The relationship of the speed of light

    c =λ f = f / ν          1/λ= ν

The Planck equation is

          E = h f

Let's start the transformations

     c = f λ = f / ν        

     f = c ν

     E = h f

     E = h c ν

     E = KT

     h c ν = K T

     T = h c ν  / K =( h c / K) ν

Let's replace the constants

     h = 6.63 10⁻³⁴ J s

     c = 3 10⁸ m / s

     K = 1.38  10⁻²³ J / K

 

     v = 1 cm-1 (100 cm / 1 m) = 10² m-1

   

     T = (6.63 10⁻³⁴ 3. 10⁸ / 1.38 10⁻²³) 1 10²

     A = h c / K = 1,441 10⁻²

     T =  1.44K

     ν = 103 cm⁻¹ = 103 10² m

     T = (6.63 10⁻³⁴ 3. 10⁸ / 1.38 10⁻²³) 103 10²

     T = 148K

1 Rydberg = 1.097 10 7 m

As we saw at the beginning the λ=1 / v

     T = (h c / K) 1 /λ

     T = 1,441 10⁻²  1 / 1,097 10⁷

     T = 1.3 10⁻⁹ K

    E = 1Ev (1.6 10⁻¹⁹ J /1 eV) = 1.6 10⁻¹⁹ J

    E = KT

    T = E/K

    T = 1.6 10⁻¹⁹ /1.38 10⁻²³

    T = 1.16 10⁴ K

3 0
3 years ago
A gas has a pressure of 220 kPa at a volume of 380K. At what temperature will the gas have a pressure of 256 kPa?
GenaCL600 [577]
The temperature will be the pressure of 130 ka
8 0
3 years ago
Two automobiles are 150 kilometers apart and traveling toward each other. One automobile
Vladimir79 [104]
Their relative speed is the sum of 60 and 40 or 100km/hr. They will travel the 150km in 1.5 hrs. When two object approach each other, the closing speed is just the sum of the speeds, therefore, the closing speed is your case is 100kph. So they will meet in 1.5 hours.
8 0
3 years ago
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