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ololo11 [35]
3 years ago
13

Half-life is the time a. For half of a material to decay into energy b. For half of a material to decay into free protons, neutr

ons, and electrons c. For half of a material to decay into a new material d. It takes to get out of school
Physics
1 answer:
aniked [119]3 years ago
6 0

Answer:

Explanation:

The half life of a radioactive substance is the time in which the activity of the radioactive substance becomes half of its initial activity.

Or

The time in which the amount of radioactive substance becomes half of its initial amount in a sample.

It is denoted by T .

The relation between the decay constant and the half life is given by

\lambda =\frac{0.693}{T}

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What is general relativity
juin [17]
General relativity is a theory of space and time. The theory was published by Albert Einstein in 1915. The central idea of general relativity is that space and time are two aspects of spacetime. Spacetime is curved when there is gravity, matter, energy, and momentum.
5 0
3 years ago
Mady has an infinite number of balls and empty boxes available to her. The empty boxes, each capable of holding four balls, are
True [87]

Answer:

The number of balls in the box at 2010th step is 6 balls

Explanation:

Since the boxes are arranged from left to right, and since the empty boxes are capable of holding 4 balls at once.

Therefore, her steps would follow this pattern ;

00001 - 1st Step

0002 - 2nd Step

0003 - 3rd Step

0004 -4th Step

0010 - 5th Step

0011 - 6th Step

0021 - 7th step

0031 - 8th step

0041 - 9th step

Looking at this pattern, it is obvious this digits are in base 5 because once we count to 4 in a unit, we move to the next at 1.

Thus,at Mady's 2010th step, we'll convert to base 5,thus 2010 in base 5 is calculated as;

2010 ÷ 5 = 402 r 0, so Base 5 is now: _ _ _ _ 0.

402 ÷ 5 = 80 r 2, so Base 5 is now: _ _ _ 2 0.

80 ÷ 5 = 16 r 0, so Base 5 is now:

_ _ 0 2 0.

16 ÷ 5 = 3 r 1, so Base 5 is now: _ 1 0 2 0.

3 ÷ 5 = 0 r 3, so Base 5 is now: 3 1 0 2 0.

So 2010 in base 10 is 31020 in base 5. Thus,the number of balls in the box at 2010th step is equal to 3 + 1 + 0 + 2 + 0 = 6balls

3 0
2 years ago
When a bat uses echolocation to determine the distance to an insect, it sends out a sound wave and waits to see how long the sou
ZanzabumX [31]

Answer:

Explanation:

Distance travelled by sound in going to target( insect )  and returning back = 2d ,d is distance of target .

time t = .06 s

speed = distance / time

344.9 = 2d / .06

d = 10.35 m

3 0
3 years ago
A child sits 1.6 m from the center of a merry go round that makes one complete revolution in 4.7 s. What is his angular accelera
olga2289 [7]

Answer: angular acceleration = 2.86\ rad/sec^{2}

Given:

Distance from center of axis = 1.6 m

Time taken to complete one revolution = 4.7 sec

Therefore, we can evaluate the angular acceleration using the following formula:

\alpha = r\times \omega^{2}

\alpha = r\times (\frac{2\pi}{T})^{2}

\alpha = 1.6\times (\frac{2\times3.14}{4.7})^{2}

\alpha = 2.86\ rad/sec^{2}

7 0
3 years ago
A LED light source contains a 0.5-Watts GaAs (Eg =1.43 eV) LED. Assuming that 0.12% of the electric energy is converted to emiss
Ray Of Light [21]

Answer:

Explanation:

energy emitted by  source per second  = .5 J

Eg = 1.43 eV .

Energy converted into radiation = .5 x .12 = .06 J

energy of one photon = 1.43 eV

= 1.43 x 1.6 x 10⁻¹⁹ J

= 2.288 x 10⁻¹⁹ J .

no of photons generated = .06 / 2.288 x 10⁻¹⁹

= 2.6223 x 10¹⁷

wavelength of photon λ = 1275 / 1.43 nm

= 891.6 nm .

momentum of photon = h / λ  ;  h is plank's constant

= 6.6 x 10⁻³⁴ / 891.6 x 10⁻⁹

= .0074 x 10⁻²⁵ J.s

Total momentum of all the photons generated

= .0074 x 10⁻²⁵  x 2.6223 x 10¹⁷

= .0194 x 10⁻⁸ Js

b ) spectral width in terms of wavelength = 30 nm

frequency width = ?

n = c / λ  , n is frequency , c is velocity of light and λ is wavelength

differentiating both sides

dn = c x dλ / λ²

given dλ = 30 nm

λ = 891.6 nm

dn = 3 x 10⁸ x 30 x 10⁻⁹ / ( 891.6  x 10⁻⁹ )²

= 11.3 x 10¹² Hz .

c )

10 nW = 10  x 10⁻⁹ W

= 10⁻⁸ W .

energy of 50 dB

50 dB = 5 B

I / I₀ = 10⁵   ;   decibel scale is logarithmic , I is energy of sound having dB = 50 and  I₀ = 10⁻¹² W /s

I = I₀ x 10⁵

= 10⁻¹² x 10⁵

= 10⁻⁷ W

= 10 x 10⁻⁸ W

power required

= 10⁻⁸ + 10 x 10⁻⁸ W

= 11  x 10⁻⁸ W.

5 0
3 years ago
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