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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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Which of the following forms of energy must an object have if it is moving at a constant velocity?
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Answer:

Kinetic energy

Explanation:

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Why is water pollution a concern if water is continuously cycled through Earth’s systems?
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Answer:Water pollution is a concern because since it is cycled threw the earths system it effect the earths system in a negative way.

Explanation:

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A block is pulled across a flat surface at a constant speed using a force of 50 newtons at an angle of 60 degrees above the hori
vladimir2022 [97]

The magnitude of the friction force is 25 N

Explanation:

To solve this problem, we just have to analyze the forces acting on the block along the horizontal direction. We have:

  • The horizontal component of the pulling force, F cos \theta, where F = 50 N is the magnitude and \theta=60^{\circ} is the angle between the direction of the force and the horizontal; this force acts in the  forward direction
  • The force of friction, F_f, acting in the backward direction

According to Newton's second law, the net force acting on the block in the horizontal direction must be equal to the product between the mass of the block and its acceleration:

\sum F_x = ma_x

where

m is the mass of the block

a_x is the horizontal acceleration

However, the block is moving at constant speed, so the acceleration is zero:

a_x = 0

So the equation becomes

\sum F_x = 0 (1)

The net force here is given by

\sum F_x = F cos \theta - F_f (2)

And so, by combining (1) and (2), we find the magnitude of the friction force:

F cos \theta - F_f = 0\\F_f = F cos \theta = (50)(cos 60^{\circ})=25 N

Learn more about  force of friction:

brainly.com/question/6217246

brainly.com/question/5884009

brainly.com/question/3017271

brainly.com/question/2235246

#LearnwithBrainly

4 0
3 years ago
Why are many adults and youth in the United states overweight?
Anna11 [10]

Answer:

I'd imagine fast food is a lot more popular than most countries over there and easier to get hold of.

Explanation:

america

6 0
2 years ago
Read 2 more answers
If the velocity of a pitched ball has a magnitude of 44.5 m/sm/s and the batted ball's velocity is 55.5 m/sm/s in the opposite d
Yuliya22 [10]

Incomplete question as the mass of baseball is missing.I have assume 0.2kg mass of baseball.So complete question is:

A baseball has mass 0.2 kg.If the velocity of a pitched ball has a magnitude of 44.5 m/sm/s and the batted ball's velocity is 55.5 m/sm/s in the opposite direction, find the magnitude of the change in momentum of the ball and of the impulse applied to it by the bat.

Answer:

ΔP=20 kg.m/s

Explanation:

Given data

Mass m=0.2 kg

Initial speed Vi=-44.5m/s

Final speed Vf=55.5 m/s

Required

Change in momentum ΔP

Solution

First we take the batted balls velocity as the final velocity and its direction is the positive direction and we take the pitched balls velocity as the initial velocity and so its direction will be negative direction.So we have:

v_{i}=-44.5m/s\\v_{f}=55.5m/s

Now we need to find the initial momentum

So

P_{1}=m*v_{i}

Substitute the given values

P_{1}=(0.2kg)(-44.5m/s)\\P_{1}=-8.9kg.m/s

Now for final momentum

P_{2}=mv_{f}\\P_{2}=(0.2kg)(55.5m/s)\\P_{2}=11.1kg.m/s

So the change in momentum is given as:

ΔP=P₂-P₁

=[(11.1kg.m/s)-(-8.9kg.m/s)]\\=20kg.m/s

ΔP=20 kg.m/s

3 0
3 years ago
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