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Zielflug [23.3K]
3 years ago
8

A wire must be replaced in a circuit by a new wire of the same material but nine times longer. If the new wire's resistance is t

he same as the original wire's, what is the diameter of the new wire?
O the same as the original diameter
O one half the original diameter
O one third the original diameter
O three times the original diameter
O nine times the original diameter
Physics
1 answer:
Blizzard [7]3 years ago
7 0

Answer:

three times the original diameter

Explanation:

From the wire's resistance formula, we can calculate the relation between the diameter of the wire and its length:

R=\rho\frac{l}{\pi \frac{d^2}{4}}\\d=\sqrt{\rho \frac{4 l}{\pi R}}\\

Here, d is the wire's diameter, \rho is the electrical resistivity of the material and R is the resistance of the wire. We have l'=9l

d'=\sqrt{\rho \frac{4 l'}{\pi R}}\\d'=\sqrt{\rho \frac{4 (9l)}{\pi R}}\\d'=3\sqrt{\rho \frac{4 l}{\pi R}}\\d'=3d

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Water is boiled at 300 kPa pressure in a pressure cooker. The cooker initially contains 3 kg of water. Once boiling started, it
Inessa [10]

Answer:

The average rate of energy transfer to the cooker is 1.80 kW.

Explanation:

Given that,

Pressure of boiled water = 300 kPa

Mass of water = 3 kg

Time = 30 min

Dryness friction of water = 0.5

Suppose, what is the average rate of energy transfer to the cooker?

We know that,

The specific enthalpy of evaporate at 300 kPa pressure

h_{f}=561.47\ kJ/kg

h_{fg}=2163.8\ kJ/kg

We need to calculate the enthalpy of water at initial state

h_{1}=h_{f}

h_{1}=561.47\ kJ/kg

We need to calculate the enthalpy of water at final state

Using formula of enthalpy

h_{2}=h_{f}+xh_{fg}

Put the value into the formula

h_{2}=561.47+0.5\times2163.8

h_{2}=1643.37\ kJ/kg

We need to calculate the rate of energy transfer to the cooker

Using formula of rate of energy

Q=\dfrac{m(h_{2}-h_{1})}{t}

Put the value into the formula

Q=\dfrac{3\times(1643.37-561.47)}{30\times60}

Q=1.80\ kW

Hence, The average rate of energy transfer to the cooker is 1.80 kW.

3 0
3 years ago
Two equal mass carts approach each other with velocities equal in magnitude but opposite in direction. Friction can be neglected
Viefleur [7K]

Answer:

0

Explanation:

Since momentum is given by:

\vec{p}=m.\vec{v}

Therefore momentum is a vector quantity in the direction of velocity.

  • Inelastic collision is the type of collision in which the masses combine after collision and start moving in the direction of the greater momentum but here in this case we have the momentum equal and opposite in direction.

<u>This case can be described mathematically as:</u>

m_1.\vec{v_1}=m_2.\vec{v_2}

since the mass and velocity are equal:

m.\vec{v}=m.\vec{v}

net momentum:

p_{net}=0

7 0
3 years ago
Please help me do this problem
Digiron [165]

Answer:

i) acceleration from B to D is 0, because the velocity is constant (stays the same)

ii) whatever units of distathat might be, we can calculate the number:

for 4 time-steps (2 to 6) the velocity is 6 per time step, that makes 24 distance units in these 4 time steps. it's the same the area underneath the graph.

there is also the vertical line from 0 to 2. we can calculate that distance like the area of a triangle with 2*6 / 2 = 6

the total distance from 0 to D is therefore 30

4 0
3 years ago
Do some research on digital vs. analog recording, and decide which you think gives the most accurate and best quality sound. Sta
rodikova [14]

Answer:

Sound quality depends on a lot of factors, and it is impossible to definitively state that either analog or digital is fundamentally better. These days, many records are made using playback of a digital file, so vinyl preference cannot be attributed solely to the differences in the way the sound wave is reproduced.

Explanation:

6 0
2 years ago
What will be the force if the particle's charge is tripled and the electric field strength is halved? Give your answer in terms
Alexus [3.1K]

Answer:

1.5F

Explanation:

Using

E= F/q

Where F= force

E= electric field

q=charge

F= Eq

So if qis tripled and E is halved we have

F= (E/2)3q

F= 1.5Eq=>> 1.5F

4 0
2 years ago
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