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Feliz [49]
3 years ago
15

How are electromagnetic waves used in the military?

Physics
1 answer:
sweet [91]3 years ago
7 0
It uses electromagnetic radiation waves to enable military communications, navigation, radar, nonintrusive inspection of aircraft, and other equipment. Hope this helps.
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You have to run 2.2 miles in track. How far is this in feet? Note: There are
Romashka [77]

Answer: B

Explanation: This can be easily done by inputting 5280 * 2.2.

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Choose all the answers that apply. Which of the following statements are true? Science is always a positive force. Animal testin
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3 years ago
Imagine two billiard balls on a pool table. Ball A has a mass of 7 kilograms and ball B has a mass of 2 kilograms. The initial v
wlad13 [49]
1) In a perfectly inelastic collision, the two balls stick together after the collision. In this type of collision, the total kinetic energy of the system is not conserved, while the total momentum is conserved.
If we callv_f the final velocity of the two balls that stick together, the conservation of the total momentum before and after the collision can be written as
m_a v_{Ai} + m_b v_{Bi} = (m_A+m_B)v_f (1)
where
m_A=7 kg is the mass of ball A
m_B=2 kg is the mass of ball B
v_{Ai}=6 m/s is the initial velocity of ball A
v_{Bi}=-12 m/s is the initial velocity of ball B (taken with a negative sign, since it goes in the opposite direction of ball A)

If we solve (1) to find v_f, we find that the final velocity of the balls is
v_f= \frac{m_Av_{Ai}+m_Bv_{Bi}}{m_A+m_B}= \frac{(7\cdot 6)+(2 \cdot (- 12))}{7+2}= \frac{18}{9}=2 m/s
and the positive sign means the two balls are going to the right.


2) I assume here we are talking about an elastic collision. In this case, both total momentum and total kinetic energy are conserved:
m_A v_{Ai}+m_B v_{Bi} = m_A v_{fA} + m_B v_{fB}
\frac{1}{2}m_A v_{Ai}^2+ \frac{1}{2}m_B v_{Bi}^2= \frac{1}{2}m_Av_{fA}^2+ \frac{1}{2}m_B v_{fB}^2
where
v_{fA} is the final velocity of ball A
v_{fB} is the final velocity of ball B

If we solve simultaneously the two equations, we find:
v_{fA}= \frac{v_{Ai}(m_A-m_B)+2m_Bv_{Bi}}{m_A+m_B} = \frac{(6)(7-2)+2(2)(-12)}{7+2}=-2 m/s
v_{fB}= \frac{v_{Bi}(m_B-m_A)+2m_Av_{Ai}}{m_A+m_B} = \frac{(-12)(2-7)+2(7)(6)}{7+2}= \frac{144}{9}=16 m/s
So, after the collision, ball A moves to the left with velocity v=-2 m/s and ball B moves to the right with velocity v=16 m/s.

3) The total momentum before and after the collision is conserved.
In fact, the total momentum before the collision is:
p_i = m_A v_{A} + m_B v_{fB} = (7\cdot 6)+(2 \cdot (-12))=42-24=18 m/s
and the total momentum after the collision is:
p_f = m_A v_{A} + m_B v_{fB} = (7\cdot (-2))+(2 \cdot 16)=-14+32=18 m/s

3 0
3 years ago
g Calculate the maximum wavelength of light that will cause the photoelectric effect for potassium. Potassium has work function
Ivahew [28]

Answer:

λ = 5.4196 10⁻⁷m,  λ = 541.96 nm    this is green ligh

Explanation:

The photoelectric effect was explained by Eintein assuming that the light was made up of particles called photons and these collided with the electrons taking them out of the material.

 

                     K = h f -Ф

where K is the kinetic energy of the ejected electrons, hf is the energy of the light quanta and fi is the work function of the material.

The speed of light is related to wavelength and frequency

                   c = λ / f

                  f = c /λ

we substitute

                K = h c / λ - Φ

for the case that they ask us the kinetic energy of the electons is zero (K = 0)

                 h c / λ = Ф

                λ = h c / Ф

we calculate

                 λ = 6.63 10⁻³⁴  3 10⁸ / 3.67 10⁻¹⁸

                 λ = 5.4196 10⁻⁷m

let's take nm

                lam = 541.96 nm

this is green light

4 0
3 years ago
In a cup of liquid water when would water molcules stop moving
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The the Water turns to ice. But even then they would never truly stop moving.<span />
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3 years ago
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