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3 years ago

What causes an electric current in a wire?

2 answers:

7 0

I think the correct answer from the choices listed above is option B. It is the electrons that flow because of electrical attraction and repulsion causes an electric current in a wire. Electrons, which continuously move in wire, are called Electric Current. Hope this answers the question.

m_a_m_a [10]3 years ago

7 0

Answer: The correct option is B.

Explanation:

The rate at which the electrons flow constitutes the electric current. The force is requires to make current flow through the wire.

There is a flow of the electrons in a wire due to the potential difference in the circuit.

The electrons always flow from high potential to the low potential. The electric force between the charged particles are important in electricity.

Unlike charges attract each other.The electrons are attracted towards the positive terminal of the battery. So, there are electrical attraction and electrical repulsion. Electrons flow because of electrical attraction and repulsion.

Therefore, the correct option us B.

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An attacker at the base of a castle wall 3.65 m high throws a rock straight up with speed 7.4m/s from a height of 1.55m above th

Natali5045456 [20]

a) Yes, the rock will reach the top

b) The final speed is 3.7 m/s

c) The change in speed is 2.4 m/s

d) The change in speed in the two situations do not agree

e) Because the kinetic energy depends quadratically on the speed, $K\propto v^2$

Explanation:

The mechanical energy of the rock at the moment it is thrown from the ground is equal to the sum of its kinetic energy and its potential energy:

$E=KE_i + PE_i = \frac{1}{2}mu^2 + mgh_i$

where

m is the mass of the rock

u = 7.4 m/s is the inital speed

$g=9.8 m/s^2$ is the acceleration of gravity

$h_i = 1.55 m$ is the initial height of the rock

Substituting, we find the initial mechanical energy of the rock

$E=\frac{1}{2}m(7.4)^2 + m(9.8)(1.55)=42.6m$ [J]

In order to reach the top of the castle, the rock should have a mechanical energy of at least

$E' = mgh'$

where

h' = 3.65 m is the heigth of the top

Substituting,

$E'=m(9.8)(3.65)=35.6m$ [J]

Since E > E', it means that the rock has enough mechanical energy to reach the top.

The final mechanical energy of the rock at the top is

$E=mgh'+ \frac{1}{2}mv^2$ (1)

where:

v is the final speed of the rock at the top

Since the mechanical energy is conserved, this should be equal to the initial mechanical energy:

$E=42.6 m$ [J] (2)

Therefore, equating (1) and (2), we can find the final speed of the rock:

$mgh' + \frac{1}{2}mv^2 = 42.6m\\v=\sqrt{2(42.6-gh')}=\sqrt{2(42.6-(9.8)(3.65))}=3.7 m/s$

Since the motion of the rock is a free fall motion (constant acceleration equal to the acceleration of gravity), we can use the following suvat equation:

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

where

v is the final speed, at the bottom

u = 7.4 m/s is the initial speed of the rock, at the top

$a=9.8 m/s^2$ is the acceleration of gravity

s = 3.65 - 1.55 = 2.1 m is the vertical displacement of the rock

Solving for v, we find the final speed:

$v=\sqrt{u^2+2as}=\sqrt{7.4^2 + 2(9.8)(2.1)}=9.8 m/s$

Therefore, the change in speed is

$\Delta v = v-u = 9.8 - 7.4 =2.4 m/s$

In the first situation (rock thrown upward), we have:

u = 7.4 m/s (initial speed)

v = 3.7 m/s (final speed)

So the change in speed is

$\Delta v = v-u =3.7 - 7.4 = -3.7 m/s$

While the change in speed in the second situation (rock thrown downward) is

$\Delta v = 2.4 m/s$

Therefore, we see that their magnitudes do not agree.

In both situations, the change in kinetic energy of the rock is equal in magnitude to the change in gravitational potential energy, since the total mechanical energy is conserved.

The change in gravitational potential energy in the two situations is the same (because the change in height is the same), therefore the change in kinetic energy in the two situations is also the same.

However, the kinetic energy of the rock is not directly proportional to the speed, but to the square of the speed:

$K\propto v^2$

Since the initial speed is the same for both situation (7.4 m/s), but the change in kinetic energy has opposite sign in the two situations (negative when the rock is thrown upward, positive when thrown downward), the situation is not symmetrical, therefore in order to have the same magnitude of change in the kinetic energy, the change in speed must be larger when the kinetic energy involved is lower, so in the first situation.

Learn more about kinetic energy and about potential energy:

brainly.com/question/6536722

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#LearnwithBrainly

6 0

4 years ago

a compound is 24.7% calcium, 1.2% hydrogen, 14.8% carbon, and 59.3% oxygen. write the empirical formula and name the compound.

Tema [17]

For simplicity, assume that the total mass of the compound is 100 g.

Therefore, by mass
Ca = 24.7 g, H = 1.2 g, C = 14.8 g, and O = 59.3 g

Converting these to moles

Mol = mass*1/atomic mass
Ca = 24.7*1/40.078 =0.6163 mol Ca
H = 1.2*1/1.01 = 1.1881 mol H
C = 14.8*1/12.01 = 1.2323 mol C
O = 59.3/16 = 3.7062 mol O

Next, divide all the mols by the smallest value obtained.

Ca: 0.6163/0.6163 = 1 mol Ca
H: 1.1881/0.6163 = 2 mol H
C: 1.2323/0.6163 = 2mol C
O: 3.7062/0.6163 = 6 mol O

Therefore, empirical formula of the compound is

CaH2C2O6

This compound is referred to as Calcium Bicarbonate

8 0

3 years ago

1) a cathode-ray tube is a type of ______ tube.

galina1969 [7]

1) Vacuum tube
2) silicon
3) integrated, I.C.s
4) this one is worded weird. Transistors are the main part of voltage regulators but they use (require) diodes and capacitors, too. And they are all put onto a microchip in the power distribution section. sorry for the long explanation.
5) away from
6) directly, inversely

4 0

3 years ago

Why does ice float on water?

WITCHER [35]

Explanation:

Ice floats on water because it's alil water compacted into 1 shape which is heavier, ice is also a solid at 1st so solid things also can float on water

6 0

3 years ago

In urban cities, power lines are plentiful and, through the use of combustion, can help transform thermal energy into electrical

Vikentia [17]

Answer:

Most likely turbines

Explanation:

Rural is the country side out of cities

7 0

4 years ago