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Anika [276]
3 years ago
6

The black board appears black because:

Physics
1 answer:
marishachu [46]3 years ago
8 0

Answer:

I think its C All visible light wavelengths (ROYGBV) are absorbed by the board

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Help help help please , i will give brainliest
finlep [7]

Answer:

I believe the answer for #1 is D and the answer for #2 is B

Explanation:

I hope this is correct and helps

6 0
3 years ago
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Radar uses radio waves of a wavelength of 2.4 \({\rm m}\) . The time interval for one radiation pulse is 100 times larger than t
blondinia [14]

Answer:

120 m

Explanation:

Given:

wavelength 'λ' = 2.4m

pulse width 'τ'= 100T ('T' is the time of one oscillation)

The below inequality express the range of distances to an object that radar can detect

τc/2 < x < Tc/2 ---->eq(1)

Where, τc/2 is the shortest distance

First we'll calculate Frequency 'f' in order to determine time of one oscillation 'T'

f = c/λ (c= speed of light i.e 3 x 10^{8} m/s)

f= 3 x 10^{8} / 2.4

f=1.25 x  10^{8} hz.

As, T= 1/f

time of one oscillation T= 1/1.25 x  10^{8}

T= 8 x 10^{-9} s

It was given that pulse width 'τ'= 100T

τ= 100 x 8 x 10^{-9} => 800 x 10^{-9} s

From eq(1), we can conclude that the shortest distance to an object that this radar can detect:

x_{min}= τc/2 =>  (800 x 10^{-9} x 3 x 10^{8})/2

x_{min}=120m

8 0
3 years ago
Which shows the order of mechanical advantage from least to greatest?
Eduardwww [97]
What do you mean? I'm confused... You need to put the rest  of the question

3 0
3 years ago
if a ball is thrown straight up into the air with an initial velocity of 8080 ft/s, its height in feet after tt second is given
yanalaym [24]

The average velocity for the time period beginning when t=1 and lasting

(i) 0.01 seconds = 63.84 ft/s

(ii) 0.001 seconds = 63.984 ft/s

Given that a ball is thrown with an initial velocity = 80 ft/s

Let 'y' be the height in feet after 't' seconds.

Given,  y=80t-16t^2 gives the height in 't' seconds.

Average velocity = Rate of change of distance

                             = Change in distance/Change in time.

The initial time can be taken as 0 s.

When t =1 s, y = 80 - 16 = 64 ft

(1)  t = 0.01 s

    y = 80 x 0.01 - 16 x 0.01 x 0.01 = 0.7984 ft

    Average velocity = (64 - 0.7984) / (1 -0.01) = 63.84 ft/s

(2) t = 0.001 s

    y = 80 x 0.001 - 16 x 0.001 x 0.001 = 0.079984 ft

    Average velocity = (64 - 0.079984) / (1 -0.001) = 63.984 ft/s

The question is incomplete. Find out the complete question below:

If a ball is thrown straight up into the air with an initial velocity of 80 ft/s, it height in feet after t second is given by  y=80t-16t^2 .Find the average velocity for the time period beginning when t=1 and lasting

(i) 0.01 seconds

(ii) 0.001 seconds

Learn more about average velocity at brainly.com/question/6504879

#SPJ4

7 0
2 years ago
Identify the breed of goat in the picture.
Step2247 [10]

Answer:

look it up im not a sheaperd sorry

Explanation:

4 0
3 years ago
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