im assuming its D. do to the sound waves having to go through more material...right?

Answer: Its B. There will be 0.031 kg left after 151 years,

Explanation: Im doing my assessment right now.

The half-life of Cs-137 is 30.2 years. If the initial mass of the sample is 1.00 kg, the mass remain after 151 years is 0.031 Kg.

Caesium-137, or radiocaesium, is a radioactive isotope of caesium that is formed as one of the more common fission products by the nuclear fission of uranium-235 and other fissionable isotopes.

Cs-137 is used in medical radiation therapy devices for treating cancer.

The half-life is the amount of time it takes for a given sample to lose half of the original amount or the time for radioactive substance to decay. The half-life of Cs-137 is 30.2 years.

Decay constant of radioactive substance is its probability of decay per unit time.

In this case,

Mass of sample is 1 Kg

Half-life of Cs-137 is 30.2 years

The elapsed time is 30.2 years.

This means, one half-life is elapsed, the half of sample will decay in 30.2 years. Therefore, the half of the original substance will remain in 30.2 years which is 0.500 Kg. After another 30.2 years, it will be 0.250 Kg. And after 151 years, it will be 0.031 Kg.

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Answer:

Pressure, P = 7 Pa

Explanation:

Given that,

Force exerted on the surface, F = 42 N

Length, l = 3 m

Width, b = 2 m

We need to find the pressure exerted by this force. We know that, pressure is equal to force per unit area. So,

[tex]P=\dfrac{F}{l\times b}\\\\P=\dfrac{42}{3\times 2}\\\\P=7\ Pa[/tex]

So, the required pressure is equal to 7 Pa.

Answer:Each goal line is 11 feet (3.4 m) from the end boards. NHL blue lines are 75 feet (22.9 m) from the end boards and 50 feet (15.2 m) apart.

Explanation:When the other team is on the attack, the defensive zone is the area between your goal line and your blue line. The central ice area between the two blue lines (neither the defending nor the attacking zone). When the your team is on the attack, the offensive zone is the area between blue line and your opponents goal.

Answer:.....................

solar panels

Answer:

D

Explanation:

Spy gear is different from Spyware.

Answer:

Standing in a moving bus may lead the person fall when the driver will apply brake.

Explanation:

According to Newton's third law of motion, there is an equal and opposite reaction to every action. When the bus is moving, the person standing is in the state of rest. The moment the driver applies brake, the bus stops. The stopping of the bus makes the person in the stationary position change in motion. Because of this force, the person may fall and collide if he is standing instead of sitting in the moving bus.

answer: the third one

Answer:

4cm

Explanation:

If it's a simple ratio 2cm:10N to ?cm:20N, It should be 4cm:20N.

Answer:

They can't hear an echo in small room because in it the sound can't be reflected back. For an echo of a sound to be heard,the minimum distance between the source of sound and the walls of the room should be 17.2 m.

hopw it helps

Answer:  B

Explanation:

Answer:

The second law of thermodynamics states that the total entropy of a system either increases or remains constant in any spontaneous process; it never decreases. ... This is because entropy increases for heat transfer of energy from hot to cold (Figure 12.9).

Explanation:

Hope It Helps

The time taken is 10 years.

The term simple interest is an interest that is charged only on the principal and not on the interest.

We have the following;

Principal =  500 birr

amount = 900 birr

rate = 8%

Interest = 900 birr - 500 birr = 400 birr

400 = 500 × 8 × T/100

400 × 100 = 500 × 8 × T

T = 400 × 100/500 × 8

T = 10 years

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Answer:

10 years

Explanation:

To solve this first we have to find the simple interest.

Let us find it now.

Interest = birr 900 - birr 500

             = birr 400

Now we are having,

Amount = birr 900

Principal = birr 500

Interest = birr 400

rate = 8%

Period of time = ?

Let us use the formula to find the period of time.

Simple interest = Principal × Rate × Time ÷ 100

birr 400  = birr 500 × 8 × t ÷ 100

birr 400 × 100 = 4000t

40000 = 4000t

Divide both sides by 4000.

10 = t

Therefore, the time is 10 years.

Let me know if you have any other questions. :-)

Answer:

Volume displaced by ducky = 75 mL = 7.5 x 10⁻⁵ m³

Mass displaced by the ducky = 7.5 x 10⁻² kg = 75 grams

Explanation:

The ducky will displace the volume of the water equal to its own volume.

Volume displaced by ducky = 75 mL = 7.5 x 10⁻⁵ m³

And the mass displaced by ducky will be equal to:

Mass displaced by the ducky = (Density of Water)(Volume displaced by ducky)

Mass displaced by the ducky = (1000 kg/m³)(7.5 x 10⁻⁵ m³)

Mass displaced by the ducky = 7.5 x 10⁻² kg = 75 grams

Answer:

distance and time of the motion

Answer:

Explanation:

First of all, I used the specific heat of water as 4182 J/(kgC) and the specific heat of ethyl alcohol (EtOH) as 2440 J/(kgC); that means that we need the masses in kg, not g.

120.g = .1200 kg of ethyl alcohol. Now for the formula:

[tex]t_f=\frac{(m_{H2O}*spheat_{H2O}*temp_{H2O})+(m_{EtOH}*spheat_{EtOH}*temp_{EtOH})}{(m_{H2O}*spheat_{H2O})+(m_{EtOH}*spheat_{EtOH})}[/tex] where spheat is specific heat.

Filling that horrifying-looking formula in with some values:

[tex]16.0=\frac{(x*4182*20.0)+(.1200*2440*10.0)}{(x*4182)+(.1200*2440)}[/tex] and

[tex]16.0=\frac{83640x+2928}{4182x+292.8}[/tex] and

16(4182x + 292.8) = 83640x + 2928 and

66912x + 4684.8 = 83640x + 2928 and

1756.8 = 16728x so

x = .105 kg and the amount of water added is 105 g

The horizontal component of velocity is

(22 m/s) • cosine(62°).

The vertical component of velocity is

(22 m/s) • sine(62°).

These are the original components, right after the kick. As time goes on, the horizontal one doesn't change. But the vertical one gets bigger and bigger, because gravity is accelerating the ball downward.

That's the complete story of projectile motion.

Answer:

16.2m/s

Explanation:

Kinetic energy=1/2mass*speed squared

KE=1/2mv^2

Data,

KE=85J

M=0.65kg

V=?

85J=1/2(0.65kg)V^2

Cross multiply

2 *85=0.65V^2

Divide both sides by 0.65

170/0.65=v^2

V=✓(170/0.65)

V= 16.172m/s

First option is collect

Answer:

The bullet that is fired will spend longer  in the air, hitting the ground after the  dropped bullet.

Explanation:

Using the equation: x =  x 0  +   v t

If we neglect the effects of air resistance, the horizontal motion is a constant velocity.

The horizontal displacement = (velocity X cosθ)

So, the fired bullet has to travel horizontally before falling which takes a  longer time compared to a bullet dropped where it is, height = 1/2 gt^2

gravity, g = 9.8 m/s2.

The time spent in air for the bullet projected at angle depends on the initial velocity of the bullet and angle of projection while bullet dropped from the same height depends on the final velocity of the bullet which depends on the height from the which the bullet was

The given parameters;

The time taken for the bullet fired at angle to return to the ground level is calculated as;

[tex]T = \frac{2 \times usin(30)}{g} \\\\T = \frac{u}{g}[/tex]

where;

The time taken for bullet dropped from the same height to reach the ground is calculated as;

[tex]v_f = v_0 + gt\\\\t = \frac{v_f - v_0}{g} \\\\t = \frac{v_f}{g}[/tex]

where

Thus, we can conclude that the time spent in air for the bullet projected at angle depends on the initial velocity of the bullet and angle of projection while bullet dropped from the same height depends on the final velocity of the bullet which depends on the height from the which the bullet was dropped.

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Answer:  

Explanation:

Answer:

0.05s

Explanation:

f=20Hz

we know,

time period=t=1/f

t=1/20

=0.05s

Answer:

Las células del interior son negativas, mientras que en el exterior son positivas.

Explanation:

Que tenga un buen día :)

If the lens of our eyes were concave, we would not be able to see. We would be blind. This is because our eyes form a visual image on the same side of the lens at the object being viewed. Thus, a concave lens would result in the visual image focusing in front of the eye, not the retina inside the eye. This would mean that no signals would be sent to the brain, and vision would not be possible.

Answer:

Explanation:

Average Speed = Total Distance / Total Time

5.3 m/s

Equation

Total distance = d1 + d2

Total Time = t1 + t2

Givens

Total Distance = 16 + 16

Total Distance = 32

Total Time = t2 + t1

Total Time = 2 sec + 4sec

Total Time = 6 sec

Solution

Average Speed = Total Distance / Total Time

Average Speed = 32 / 6

Average Speed = 5.33 m/s

Answer:

η = 0.882 = 88.2 %

Explanation:

The efficiency of the pulley system can be given as follows:

[tex]\eta = \frac{W_{out}}{W_{In}}\\\\[/tex]

where,

η = efficiency of pulley system = ?

W_out = Output Work = (600 N)(0.6 m) = 360 J

W_in = Input Work = (35.7 N)(11.43 m) = 408.051 J

Therefore,

[tex]\eta = \frac{360\ J}{408.051\ J}[/tex]

η = 0.882 = 88.2 %

Answer:

boundary

Explanation:

Answer:

yaa

Explanation:

Explanation:

i am sooo sorry it will take a lot of time if I copy the sentences,. all answers are correct.

hope this helps you to.

Answer: The crest of one wave overlaps with the trough of another

Explanation:

I took the test and got 100%. This is the correct answer

The best description of the destructive interference of light is the crest of one wave overlaps with the trough of another.

Destructive interference takes place when waves come together in such a manner that they completely cancel each other out or amplitude of the resulting wave decreased.

The highest surface part of a wave is called the crest, and the lowest part is the trough.

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Answer:

Current, I = 4.75 Amps

Explanation:

Given the following data;

Voltage = 19 V

Resistance = 4 Ohms

To find the current;

Ohm's law states that at constant temperature, the current flowing in an electrical circuit is directly proportional to the voltage applied across the two points and inversely proportional to the resistance in the electrical circuit.

Mathematically, Ohm's law is given by the formula;

[tex] V = IR[/tex]

Where;

V represents voltage measured in voltage.

I represents current measured in amperes.

R represents resistance measured in ohms.

Making current (I) the subject of formula, we have;

[tex] I = \frac {V}{R} [/tex]

Substituting into the formula, we have;

[tex] I = \frac {19}{4} [/tex]

Current, I = 4.75 Amps