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3 years ago

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Two boys searching for buried treasure are standing underneath the same tree. One boy walks 18 m east and then 18 m north. The o

ther boy walks 16 m west and then 11 m north. Find the scalar product of their net displacements from the tree.

1 answer:

Sati [7]3 years ago

7 0

It is 15.75 but u can put 16

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What is the wavelength of a radio wave with a frequency of 2.00 x 10^4 Hz? (hint: what is the speed of all electromagnetic radia

patriot [66]

Answer: Option B

The wavelength for a radio wave with a frequency of 2 × 10⁴ Hz is

1.5 × 10⁴ m.

Explanation:

Wavelength is the measure of distance between two successive crests or troughs in a standing wave. Also wavelength can be measured as the ratio of velocity of light to frequency. It is like this because wavelength is inversely proportional to the frequency.

$Wavelength =\frac{c}{frequency}$

As c = 3 × 10⁸ m/s and the frequency is 2 × 10⁴ Hz, then the wavelength will be

$Wavelength =\frac{3*10^{8} }{2*10^{4} } =1.5*10^{4} m$

So, the wavelength for a radio wave with a frequency of 2 × 10⁴ Hz is

1.5 × 10⁴ m.

5 0

3 years ago

Need help with this! <br><br> just scienceeeeeee

LiRa [457]

Answer:

7) λ = 0.5 m, 8) f = 4.8 10¹⁴ Hz

Explanation:

The speed of an electromagnetic wave is

c = λ f

where c is the speed of light in vacuum c = 3 10⁸ m / s

7) indicate the frequency f = 6.0 10⁸ Hz

we do not know the wavelength

λ = c / f

we calculate

λ = 3 10⁸ / 6.0 10⁸

λ = 0.5 m

8) indicate the wavelength λ = 6.25 10-7 m

we do not know the frequency

f = c / λ

we calculate

f = 3 10⁸ / 6.25 10⁻⁷

f = 0.48 10¹⁵ Hz

f = 4.8 10¹⁴ Hz

8 0

3 years ago

A rock slides down from A to B along the inside surface of a frictionless hemispherical bowl. As the rock slides, mechanical ene

DIA [1.3K]

Answer:

the normal force on the rock acts perpendicular to the bowl's surface.

Explanation:

As we know that Normal force is the reaction force of two contact surfaces which always act perpendicular to the contact surfaces

Here we know that the rock is moving inside the bowl

So Normal force on the rock must perpendicular to the surface of the bowl which always passes through the center of the bowl.

Since the rock is moving in vertical plane so it must have two acceleration

1) Tangential acceleration which will increase the magnitude of the speed along the tangential path

2) Centripetal acceleration which will change the direction of the rock

So here only correct option will be

the normal force on the rock acts perpendicular to the bowl's surface.

6 0

3 years ago

MariettaO [177]

Kinetic energy is dependent on Its position

3 0

3 years ago

You place an object 30.0 cm from a concave mirror of 15.0 cm focal length. The object is 1.8 cm tall. Find the image position an

Softa [21]

Answer:30 cm

Explanation:

Given

object distance $u=30\ cm$

focal length of concave mirror $f=15\ cm$

height of object $h_o=1.8\ cm$

Using mirror formula

$\Rightarrow \frac{1}{v}+\frac{1}{u}=\frac{1}{f}$

$\Rightarrow \frac{1}{v}=\frac{1}{15}-\frac{1}{30}$

$\Rightarrow \frac{1}{v}=\frac{2-1}{30}$

$\Rightarrow v=30\ cm$

and magnification is

$\Rightarrow m=\frac{-v}{u}=\frac{h_i}{h_o}$

$\Rightarrow \frac{-30}{30}=\frac{h_i}{1.8}$

$\Rightarrow h_i=-1.8\ cm$

So height of object is same as of object .

Position :image is formed at the spot where object is placed.

4 0

3 years ago