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3 years ago

How are work and power related?

Physics

2 answers:

Sholpan [36]3 years ago

6 0

Work involves force and power is the amount of work in a certain time

VashaNatasha [74]3 years ago

5 0

Answer: Work done is a measure of the energy transferred when a force moves a load, power is the rate of energy transfer.

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A 6.50-m-long iron wire is 1.50 mm in diameter and carries a uniform current density of 4.07 MA/m^2. Find the voltage between th

Sauron [17]

Answer:

V = 0.45 Volts

Explanation:

First we need to find the total current passing through the wire. That can be given by:

Total Current = I = (Current Density)(Surface Area of Wire)

I = (Current Density)(2πrL)

where,

r = radius = 1.5/2 mm = 0.75 mm = 0.75 x 10⁻³ m

L = Length of Wire = 6.5 m

Therefore,

I = (4.07 x 10⁻³ A/m²)[2π(0.75 x 10⁻³ m)(6.5 m)]

I = 1.25 x 10⁻⁴ A

Now, we need to find resistance of wire:

R = ρL/A

where,

ρ = resistivity of iron = 9.71 x 10⁻⁸ Ωm

A = Cross-sectional Area = πr² = π(0.75 x 10⁻³ m)² = 1.77 x 10⁻⁶ m²

Therefore,

R = (9.71 x 10⁻⁸ Ωm)(6.5 m)/(1.77 x 10⁻⁶ m²)

R = 0.36 Ω

From Ohm's Law:

Voltage = V = IR

V = (1.25 x 10⁻⁴ A)(0.36 Ω)

V = 0.45 Volts

4 0

3 years ago

What forces keep an air hockey puck hovering motionless above an air hockey table?

Mnenie [13.5K]

C. the puck's weight and the air blowing

4 0

3 years ago

Read 2 more answers

A length of copper wire carries a current of 11 A, uniformly distributed through its cross section. Calculate the energy density

NISA [10]

Answer:

a) $0.983 \frac{J}{m^3}$

b) $u_E =7.329x10^-3 \frac{J}{m^3}$

Explanation:

The energy density is "the energy per unit volume, in the electric field. The energy stored between the plates of the capacitor equals the energy per unit volume stored in the electric field times the volume between the plates".

A magnetic field is a "vector field that describes the magnetic influence of electric charges in relative motion and magnetized materials".

Part a

For this case we can assume use the equation for the magnetic field in terms of the energy per unit of volume.

$B=\sqrt{2\mu_o u}$

Where μ0 represent the permeability constant, also known as the magnetic constant. If we solve for u we got:

$u=\frac{B^2}{2\mu_o}$

We also know that the magnetic field can be expressed in terms of the current and the radius of action R like this:

$B=\frac{\mu_o i}{2\pi R}$

Replacing this on the formula for u we have:

$u=\frac{1}{2\mu_o}(\frac{\mu_o i}{2\pi R})^2$

And simplyfing we got:

$u=\frac{\mu_o i^2}{8\pi^2 R^2}$

Replacing the values given we have:

$u=\frac{(4\pix10^{-7} \frac{H}{m} (11A)^2}{8\pi^2 (0.0014m)^2} =0.983 \frac{J}{m^3}$

Part b

The density current is given by this formula $J=i/A$ and the resistance by $R=\frac{\rho l}{A}$

If we use the equation for the energy density we have this:

$u_E =\frac{1}{2}\varepsilon_o E^2 =\frac{\varepsilon}{2}(\rho J)^2=\frac{\varepsilon}{2}(\frac{iR}{l})^2$

And replacing the values given we have:

$u_E =\frac{8.85x10^{-12}\frac{F}{m}}{2}(\frac{11A(3700\frac{\Omega}{m})}{l})^2 =7.329x10^-3 \frac{J}{m^3}$

4 0

3 years ago

You illuminate a slit with a width of 77.7 μm with a light of wavelength 721 nm and observe the resulting diffraction pattern on

SVETLANKA909090 [29]

Answer:

The width is $Z = 0.0424 \ m$

Explanation:

From the question we are told that

The width of the slit is $d = 77.7 \mu m = 77.7 *10^{-6} \ m$

The wavelength of the light is $\lambda = 721 \ nm$

The position of the screen is $D = 2.83 \ m$

Generally angle at which the first minimum of the interference pattern the light occurs is mathematically represented as

$\theta = sin ^{-1}[\frac{m \lambda}{d} ]$

Where m which is the order of the interference is 1

substituting values

$\theta = sin ^{-1}[\frac{1 *721*10^{-9}}{ 77.7*10^{-6}} ]$

$\theta = 0.5317 ^o$

Now the width of first minimum of the interference pattern is mathematically evaluated as

$Y = D sin \theta$

substituting values

$Y = 2.283 * sin (0.5317)$

$Y = 0.02 12 \ m$

Now the width of the pattern's central maximum is mathematically evaluated as

$Z = 2 * Y$

substituting values

$Z = 2 * 0.0212$

$Z = 0.0424 \ m$

3 0

3 years ago

The velocity of a ball as it is thrown up is 20 meters/second. It attains zero velocity after 3.5 seconds. What is the average a

iogann1982 [59]

The average acceleration is

$\bar a=\dfrac{\Delta v}{\Delta t}=\dfrac{0\,\frac{\mathrm m}{\mathrm s}-20\,\frac{\mathrm m}{\mathrm s}}{3.5\,\mathrm s-0\,\mathrm s}=-5.7\,\dfrac{\mathrm m}{\mathrm s^2}$

so the answer is D.

6 0

3 years ago

Read 2 more answers