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2 years ago

The resistivity of

Physics

1 answer:

Pachacha [2.7K]2 years ago

5 0

The current density of the copper wire is determined as (7.059 x 10⁸ A/m²)/L

<h3>Current density of the copper wire</h3>

The current density of the copper wire is calculated as follows;

J =1/ρ(E) = 1/ρ(V/L)

where;

E is electric field
V is voltage
L is length of the wire

<h3>Current density the wire</h3>

J =1/ρ(E) = 1/ρ(V/L)

J = (1/1.7 x 10⁻⁸) x (12)/L

J = (7.059 x 10⁸ A/m²)/L

Learn more about current here: brainly.com/question/24858512

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it takes 90 j of work to stretch a spring 0.2 m from its equilibrium position. How muc work is needed to stretch it an additiona

Vinvika [58]

Work needed: 720 J

Explanation:

The work needed to stretch a spring is equal to the elastic potential energy stored in the spring when it is stretched, which is given by

$E=\frac{1}{2}kx^2$

where

k is the spring constant

x is the stretching of the spring from the equilibrium position

In this problem, we have

E = 90 J (work done to stretch the spring)

x = 0.2 m (stretching)

Therefore, the spring constant is

$k=\frac{2E}{x^2}=\frac{2(90)}{(0.2)^2}=4500 N/m$

Now we can find what is the work done to stretch the spring by an additional 0.4 m, that means to a total displacement of

x = 0.2 + 0.4 = 0.6 m

Substituting,

$E'=\frac{1}{2}kx^2=\frac{1}{2}(4500)(0.6)^2=810 J$

Therefore, the additional work needed is

$\Delta E=E'-E=810-90=720 J$

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7 0

3 years ago

Stress distributed over an area is best described as: a) External force b) Axial force c) Radial force d) Internal resistive for

Anit [1.1K]

Answer:

Option D is the correct answer.

Explanation:

Stress is the force per unit area that tend to change the shape of body.

Stress is defined as internal resistive force per unit area.

$\texttt{Stress}=\frac{\texttt{Internal resistive force}}{\texttt{Area}}$

$\sigma =\frac{F}{A}$

So, so stress distributed over an area is best described as internal resistive force.

Option D is the correct answer.

8 0

3 years ago

A sled of mass 2.12 kg has an initial speed of 5.49 m/s across a horizontal surface. The coefficient of kinetic friction between

Darya [45]

Answer:

The speed of the sled is 3.56 m/s

Explanation:

Given that,

Mass = 2.12 kg

Initial speed = 5.49 m/s

Coefficient of kinetic friction = 0.229

Distance = 3.89 m

We need to calculate the acceleration of sled

Using formula of acceleration

$a = \dfrac{F}{m}$

Where, F = frictional force

m = mass

Put the value into the formula

$a=\dfrac{\mu mg}{m}$

$a=\mu g$

$a=0.229\times9.8$

$a=2.244\ m/s^2$

We need to calculate the speed of the sled

Using equation of motion

$v^2=u^2-2as$

Where, v = final velocity

u = initial velocity

a = acceleration

s = distance

Put the value in the equation

$v ^2=(5.49)^2-2\times2.244\times3.89$

$v=\sqrt{(5.49)^2-2\times2.244\times3.89}$

$v=3.56\ m/s$

Hence, The speed of the sled is 3.56 m/s.

8 0

3 years ago

Which occurs at a transform boundary?

andreev551 [17]

The answer is B. One plate slides past another.

The San Andreas Fault in California and the Alpine Fault in New Zealand are examples of transform boundaries.

Hope this helps! :)

5 0

3 years ago

You have designed a machine that requires 1000 J of work from a motor for every 800 J of useful work done by the machine. What i

valentinak56 [21]

Answer:

80%

Explanation:

$efficiency = \frac{useful \: work \: done}{total \: energy \: input}$

800 / 1000 = 0.8

Efficiency = 0.8 *100 = 80%

4 0

2 years ago