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zzz [600]
3 years ago
5

What is the frequency of 20 mm microwaves? A) 100 MHz B) 400 MHz C) 15 GHz D) 73 GHz E) 98 GHz

Physics
1 answer:
Lera25 [3.4K]3 years ago
3 0

Answer:

Explanation:

Given wavelength  = 20 mm = 20 x 10⁻³ m

The microwaves are electromagnetic waves so their velocity will be equal to

3 x 10⁸ m /s.

Now frequency of microwave = velocity / wavelength

= 3 x 10⁸ / 20 x 10⁻³ = 1.5 x 10¹⁰ = 15 x 10⁹ = 15 GHz.

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How much power is needed to lift a 20-kg object to a height of 4.0 m in 2.5 seconds?
4vir4ik [10]

Answer:

313.92w

Explanation:

Formula for power:

P=W/∆t = Fv

Givens:

m=20kg

∆y=4.0m

∆t=2.5s

a=9.81m/s²

In order to find power, we first need to solve for work.

W=Fd (force*displacement), f=mg

W=mg∆y

W=(20kg)(9.81m/s²)(4.0m)

W=784.8J

P=W/∆t

P=784.8J/2.5s

P=313.92 watts

5 0
3 years ago
A driver of a car enters a new 110 km/h speed zone on the highway. The driver begins to accelerate immediately and reaches 110 k
levacccp [35]

Answer:

30Km/h

Explanation:

acceleration is the change of speed in a given time so when we substract the accelerations we can know how much the car goes per an hour

3 0
3 years ago
Describe two sources of earth's energy that are not produced
Anvisha [2.4K]
Here is the answer. Two sources of Earth's energy that are not produced would be Cosmic rays and Tidal Energy. Cosmic rays <span>are high-energy protons and atomic nuclei that come from outside the solar system. Whereas, tidal energy is the energy produced by both the moon (2/3) and the sun (1/3). Hope this answers your question.</span>
6 0
3 years ago
What would happen if brains weren't flexible
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3 0
3 years ago
A 25 kg block is held against a compressed spring and then the spring is allowed to decompress giving the block a velocity. The
Alex787 [66]

Answer:

h=18.05 cm

Explanation:

Given that

m= 25 kg

K= 1300 N/m

x=26.4 cm

θ= 19.5 ∘

When the block just leave the spring then the speed of block = v m/s

From energy conservation

\dfrac{1}{2}Kx^2=\dfrac{1}{2}mv^2

Kx^2=mv^2

v=\sqrt{\dfrac{kx^2}{m}}

By putting the values

v=\sqrt{\dfrac{kx^2}{m}}

v=\sqrt{\dfrac{1300\times 0.264^2}{25}}

v=1.9 m/s

When block reach at the maximum height(h) position then the final speed of the block will be zero.

We know that

V_f^2=V_i^2-2gh

By putting the values

0^2=1.9^2-2\times 10\times h

h=0.1805 m

h=18.05 cm

4 0
3 years ago
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