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2 years ago

What term defines the specific amount of time required for half of a radioactive substance to become stable?

Physics

1 answer:

Tanya [424]2 years ago

5 0

A would be the answer because thats how long it takes

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Why doesn't the motor work?

exis [7]

Answer:

Explanation: its weird

8 0

3 years ago

Unpolarized light with intensity I0I0I_0 is incident on an ideal polarizing filter. The emerging light strikes a second ideal po

zvonat [6]

Answer:

$0.293I_0$

Explanation:

When the unpolarized light passes through the first polarizer, only the component of the light parallel to the axis of the polarizer passes through.

Therefore, after the first polarizer, the intensity of light passing through it is halved, so the intensity after the first polarizer is:

$I_1=\frac{I_0}{2}$

Then, the light passes through the second polarizer. In this case, the intensity of the light passing through the 2nd polarizer is given by Malus' law:

$I_2=I_1 cos^2 \theta$

where

$\theta$ is the angle between the axes of the two polarizer

Here we have

$\theta=40^{\circ}$

So the intensity after the 2nd polarizer is

$I_2=I_1 (cos 40^{\circ})^2=0.587I_1$

And substituting the expression for I1, we find:

$I_2=0.587 (\frac{I_0}{2})=0.293I_0$

5 0

2 years ago

A uniform disk with a mass of 5.0 kg and diameter 30 cm rotates on a frictionless fixed axis through its center and perpendicula

igomit [66]

Answer:

Angular acceleration of the disk will be $\alpha =10.714rad/sec^2$

Explanation:

We have given mass of the disk m = 5 kg

Diameter of the disk d = 30 cm = 0.3 m

So radius $r=\frac{d}{2}=\frac{0.3}{2}=0.15m$

Moment of inertia of disk is given by $I=\frac{1}{2}mr^2=\frac{1}{2}\times 5\times 0.15^2=0.056kgm^2$

Force is given by F=4 N

Torque is given as $\tau =Fr=4\times 0.15=0.6N-m$

We also know that torque is given by $\tau =I\alpha$

$0.6=0.056\times \alpha$

$\alpha =10.714rad/sec^2$

5 0

3 years ago

A star is moving away from an observer at 1% of the speed of light. At what wavelength would the observer find an emission line

Ivan

Answer:

λ = 5940 Angstroms

Explanation:

This is an exercise of the relativistic Doppler effect

f’= f √((1- v / c) / (1 + v / c))

Where the speed in between the strr and the observer is positive if they move away

Let's use the relationship

c = λ f

f = c /λ

We replace

c /λ’ = c /λ √ ((1- v / c) / (1 + v / c))

λ = λ’ √ ((1- v / c) / (1 + v / c))

Let's calculate

v = 0.01 c

v = 0.01 3 10⁸

v= 3 10⁶ m / s

λ = 6000 √ [(1- 3 10⁶/3 10⁸) / (1+ 3 10⁶/3 10⁸)]

λ = 6000 √ [0.99 / 1.01]

λ = 5940 Angstroms

6 0

3 years ago

Which of the following results when a crest and trough meet?

kifflom [539]

D. Destructive interference. An easy way to think about it is the waves are opposite each other, so they essentially cancel each other out, or make an effort to.

6 0

3 years ago