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2 years ago

9

if A and B are non zero vectors, is it possible for vector A×vector B and vector A.vector B both to be zero? Justify your answer

1 answer:

DedPeter [7]2 years ago

3 0

Answer:

not able to understand the question

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What is the momentum of a photon having the same total energy as an electron with a kinetic energy of 100 keV?

statuscvo [17]

Answer:

The momentum of the photon is 1.707 x 10⁻²² kg.m/s

Explanation:

Given;

kinetic of electron, K.E = 100 keV = 100,000 eV = 100,000 x 1.6 x 10⁻¹⁹ J = 1.6 x 10⁻¹⁴ J

Kinetic energy is given as;

K.E = ¹/₂mv²

where;

v is speed of the electron

$K.E = \frac{1}{2}mv^2\\\\mv^2 = 2K.E \\\\v^2 = \frac{2K.E}{m} \\\\v = \sqrt{\frac{2K.E}{m}} \\\\but \ momentum ,P = mv\\\\(v)m = (\sqrt{\frac{2K.E}{m}})m\\\\P_{photon} = (\sqrt{\frac{2K.E}{m_e}})m_e\\\\P_{photon} = (\sqrt{\frac{2\times 1.6\times 10^{-14}}{9.11\times10^{-31}}})(9.11\times 10^{-31})\\\\P_{photon} = 1.707 \times 10^{-22} \ kg.m/s$

Therefore, the momentum of the photon is 1.707 x 10⁻²² kg.m/s

6 0

3 years ago

A stone is thrown vertically upwards with an initial velocity of 20m/sec. Find the maximum height ot reaches and the time taken

MAXImum [283]

Answer:

The height reached is 20m, The time taken to reach 20m is 2 seconds

Explanation:

Observing the equations of motion we can see that the following equation will be most helpful for this question.

$v^{2} = u^{2} + 2as$

We are given initial velocity, u

We know that the stone will stop at its maximum height, so final velocity, v

Acceleration, a

And we are looking for the displacement (height reached), s

Substitute the values we are given into the equation

$0^{2} = 20^{2} + 2(10)s$

Rearrange for s

$0^{2} -20^{2} =20s$

$-400=20s$

$\frac{-400}{20} =s$

s = -20 (The negative is just showing direction, it can be ignored for now)

The height reached is 20m

Use a different equation to find the time taken

$s = vt - \frac{1}{2} at^{2}$

Substitute in the values we have

$-20=(0)t - \frac{1}{2} (10)t^{2}$

Rearrange for t

$-20 =0 -5 t^{2}$

$\frac{-20}{-5} =t^{2}$

$4 = t^{2}$

t = 2s

The time taken to reach 20m is 2 seconds

4 0

3 years ago

Protons have a positive charge<br><br> A.True<br> B.False

PIT_PIT [208]

Answer:

TRUE

Explanation:

Protons have a positive charge. Electrons have a negative charge. The charge on the proton and electron are exactly the same size but opposite. Neutrons have no charge.

5 0

3 years ago

Read 2 more answers

A car is traveling down the highway at speed 5 m/s when the driver slams on the brakes and skids to a stop in a distance 80 m. A

Murljashka [212]

The car is very incredibly fast

8 0

3 years ago

The resistance between 2 points in an electrical circuit is 1.1 Ω. What additional resistance

valentinak56 [21]

Answer:

the new resister is 11 ohms.

Explanation:

Set it up like this.

1/x + 1/1.1 = 1 Subtract 1/1.1 from both sides

1/x = 1 - 1/1.1

1 - 1/1.1 = 1/11

1/x = 1/11 Cross multiply

11 = x

If 1/11 bothers you, you could do it it another way.

1 - 1/1.1 = (1.1 - 1 ) / 1.1 = 0.1 / 1.1 Multiply top and bottom by 10

0.1*10/(1.1 * 10 ) = 1 / 11

5 0

3 years ago