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2 years ago

What is the difference between a bar magnet and an electromagnet? (check all that are

Physics

1 answer:

lukranit [14]2 years ago

5 0

Answer:

D and A

Explanation:

Hint The basic difference between them is that a bar magnet is a permanent magnet whereas an electromagnet is a temporary magnet. An electromagnet is formed when an electric current is passed through wires wound around soft metalcore. An electromagnet loses its magnetism once the current flow is stopped.

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A ball of radius r rolls on the inside of a track of radius R. If the ball starts from rest at the vertical edge of the track, f

meriva

Answer:

$v=\sqrt{\dfrac{10g(R-r)}{7}}$

Explanation:

Given that

Radius of track = R

Radius of ball = r

The ball can be treated as solid sphere, so

The moment of inertia of ball

$I=\dfrac{2}{5}mr^2$

When the ball reach at the lowest position then it will have both angular and linear speed.

Condition for rolling without slipping v= ωr

Form energy conservation

$mgR=mgr+\dfrac{1}{2}mv^2+\dfrac{1}{2}I\omega^2$

v= ωr

$I=\dfrac{2}{5}mr^2$

$mgR=mgr+\dfrac{1}{2}mv^2+\dfrac{1}{2}\times \dfrac{2}{5}mr^2\omega^2$

$mg(R-r)=\dfrac{1}{2}mv^2+\dfrac{1}{2}\times \dfrac{2}{5}mv^2$

$2mg(R-r)=mv^2+\dfrac{2}{5}mv^2$

$2g(R-r)=\dfrac{7}{5}v^2$

$v=\sqrt{\dfrac{10g(R-r)}{7}}$

3 0

2 years ago

The energy required to dislodge electrons from sodium metal via the photoelectric effect is 275 kj/mol. What wavelength in nm of

denis23 [38]

Answer: 430 nm

Explanation:

For 257 kJ to dislodge one mole of electrons we need,

275 x 10^3 / 6 x 10^23 = 4.6 x 10^-19

Using Einstein’s relationship between energy, frequency and wavelength

E = hf = h x (c/landa)

Therefore

Landa = h x (c/E) = 6.6 x 10^-34 x (3 x 10^8 / 4.6 x 10^-19 = 4.3 x 10-7 m.

In nm, landa = 430 nm

7 0

3 years ago

What would most likely happen if the power lines in a pretroleum power plant were broken

tatiyna

If a power lines in a petroleum power plant were broken CUSTOMERS WOULD NOT RECEIVE ELECTRICITY.
Power lines are used in electrical power transmission to transmit electrical energy across large distances. When these lines are broken, the generating plant will not be able to send electricity across to the consumers.

4 0

3 years ago

Copernicus's model of the universe differs from Ptolemy's because Copernicus believed

Aneli [31]

Answer:

That the Sun was the center of the universe.

Explanation:

Ptolemy believed in geocentrism, which means that the Earth is the center of the Universe. This was also supported by Aristotle. Copernicus on the other hand believed in a heliocentric system, which proposes that the sun is the center of the universe.

4 0

2 years ago

Read 2 more answers

Emily holds a banana of mass m over the edge of a bridge of height h. She drops the banana and it falls to the river below. Use

Mariana [72]

Answer:

The mass of the banana is m and it is at height h.

Applying the Law of Conservation of Energy

Total Energy before fall = Total Energy after fall

$E_{i}$ = $E_{f}$