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Elanso [62]
2 years ago
11

If the radius of a coinis 20cm, find itssurface area -​

Physics
1 answer:
meriva2 years ago
8 0

Answer:

800\picm²

Explanation:

Given parameters:

radius of the coin  = 20cm

Unknown:

Surface area of the coin  = ?

Solution:

A coin is made up of two faces;

  Surface area  = 2(πr²)

Insert the parameters and solve;

     Surface area = 2(\pi  x 20^{2})

    Surface area = 800\picm²

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Three point charges, two positive and one negative, each having a magnitude of 20 C are placed at the vertices of an equilateral
Daniel [21]

The resultant force on the positive charge  is mathematically given as

X=40N

<h3>What is the magnitude of the electrostatic force on the negative charge?</h3>

Question Parameters:

Three-point charges, two positive and one negative, each having a magnitude of 20

Generally, the -ve charge   is mathematically given as

Q+=\sqrt{x^2+x^2+2x.xcos120}\\\\Q+=\sqrt{2x^2+2x*(1/2)}

Q+=X

Therefore

x=\frac{Kq1q2}{r2}\\\\x=\frac{9*10^9*20*10^{-6}*20*10^{-6}}{(30*10^-2)^2}

X=40N

For more information on Force

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5 0
2 years ago
An object is placed 4.0 cm to the left of a convex lens with a focal length of +8.0 cm . Where is the image of the object?
Serjik [45]

The image of the object is 8cm to the left of the lens (D)

<h3></h3>

What is the image of an object?

The image of an object is said to be the location where light rays from that object intersect with a mirror by reflection.

It is calculated thus:

1÷v = 1÷f - 1÷u

<h3>How to calculate the image of an object</h3>

From the formula

1÷v = 1÷f - 1÷u

<h3>Where </h3>

V = image distance fromthe object

U = object

f = focal length

Substitute the values

1÷v = 1÷8 - 1÷ 4

1÷v = - 1÷8

Make v the subject of formula

v = -8cm

Therefore, the image of the object is 8cm to the left of the lens (D)

Learn more on focal length here:

brainly.com/question/25779311

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6 0
2 years ago
Bottlenose dolphins use echolocation pulses with a frequency of about 100 kHz, higher than the frequencies used by most bats. Wh
Alinara [238K]

Answer:

1. greater

2. direct

3. smaller

4. inverse

Explanation:

The speed of sound in water is greater than in air; hence for the same frequency the sound wavelength in water is <u>greater </u>than in air (for the given frequency the wavelength is in the <u>direct </u>proportion with the speed of sound).

To "see" an object via the echolocation creature needs to use sound with the wavelength <u>smaller </u>than the size of an object viewed.

That means to "see" objects of the same size dolphin and bat need to use ultrasound of the same wavelength, hence dolphin needs to use higher frequency (for the given speed of sound the wavelength is in <u>inverse </u>proportion with the frequency).

8 0
2 years ago
Two pine cones are falling from a pine tree. Both pine cones are falling at the same speed.
elena-14-01-66 [18.8K]

Answer:

Pine cone 2 does, the more mass an object has, the more kinetic energy is has.

Explanation:

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2 years ago
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17.15 :)

rigt on ur mom

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