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3 years ago

(1 point) find the half-life (in hours) of a radioactive substance that is reduced by 1010 percent in 9595 hours.

1 answer:

8 0

The decay function is of the form
$N(t) = N_{0} \, e^{-kt}$
where
N₀ = initial amount
k = decay constant
t = hours

The material decays by 10% in 95 hours. Therefore
$0.9N_{0} = N_{0} \, e^{-95k} \\\\ -95k = ln(0.9) \\\\ k= \frac{ln(0.9)}{-95}=0.001109$

The time for the half life is given by
$0.5N_{0} = N_{0} \, e^{-0.001109t} \\\\ -0.0001109t = ln(0.5) \\\\ t = \frac{ln(0.5)}{-0.001109} = 625 \, h$

Answer: The half life is 625 hours

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Match the words in the left-hand column to the appropriate blank in the sentences in the right-hand column. Use each word only o

Vlad [161]

Answer:

1. About a trillion comets are thought to be located far, far beyond Pluto in the Oort cloud.

2. The bright spherical part of a comet observed when it is close to the Sun is the coma .

3. A comet's plasma tail stretches directly away from the Sun.

4. A comet's nucleus is the frozen portion of a comet.

5. Particles ejected from a comet can cause a(n) meteor shower on Earth.

6. The Kuiper belt extends from about beyond the orbit of Neptune to about twice the distance of Neptune from the Sun.

Explanation:

1. Oort cloud is a theoretical cloud of icy objects in interstellar space. Its inner limit begins about 2000-5000 AU from sun outer limit (about 100000-200000 AU) defines the boundary of solar system.

Note: AU is the astronomical unit which is defined as the distance between the Sun and Earth.

2. Comets are described as “dirty snowballs” which is a mixture of frozen gases and dust. When this snowball gets closer to the Sun, gas evaporates, and a fuzzy haze of gas and dust emerges. This fuzzy tail is the coma.

3. Dust and gas in the coma interact with the sunlight and the solar wind. Charged particles in the coma are caught up in the magnetic field of sun and flow away from the sun.

4. Nucleus is the dirty snowball which consists of rock, dust and frozen gas.

5. Meteor shower is a celestial event with number of meteors can be observed. Meteors are meteoroids that enters earth’s atmosphere with extremely high speeds.

6. Kuiper belt is a region beyond Neptune including dwarf planets and icy objects.

5 0

3 years ago

A 125kg bumper car going 12m/s hits a 235kg bumper car going -13m/s.if the first car bounces back at -12.5m/s what is the veloci

vovikov84 [41]

According to the law of conservation of momentum:

$m_{1}v_{1}+m_{2}v_{2}=m_{1}v_{1}'+m_{2}v_{2}'$

m1 = mass of first object
m2 = mass of second object
v1 = Velocity of the first object before the collision
v2 = Velocity of the second object before the collision
v'1 = Velocity of the first object after the collision
v'2 = Velocity of the second object after the collision

Now how do you solve for the velocity of the second car after the collision? First thing you do is get your given and fill in what you know in the equation and solve for what you do not know.

m1 = 125 kg v1 = 12m/s v'1 = -12.5m/s
m2 = 235kg v2 = -13m/s v'2 = ?

$m_{1}v_{1}+m_{2}v_{2}=m_{1}v_{1}'+m_{2}v_{2}'$
$(125kg)(12m/s)+(235kg)(-13m/s)=(125kg)(-12.5m/s)+(235kg)(v_{2}'$
$1,500kg.m/s+(-3055kg.m/s)=(-1562.5kg.m/s)+(235kg)(v_{2}')$
$-1,555kg.m/s=(-1562.5kg.m/s)+(235kg)(v_{2}')$

Transpose everything on the side of the unknown to isolate the unknown. Do not forget to do the opposite operation.

$-1,555kg.m/s + 1562.5kg.m/s=(235kg)(v_{2}')$
$7.5kg.m/s=(235kg)(v_{2}')$
$(7.5kg.m/s)/(235kg)=(v_{2}')$
$0.03m/s=(v_{2}')$

The velocity of the 2nd car after the collision is 0.03m/s.

5 0

3 years ago

The radius of curvature of both sides of a converging lens is 18 cm. One side of the lens is coated withsilver so that the inner

Dahasolnce [82]

Answer:

n = 1.4

Explanation:

Given,

R1 = 18 cm, R2 = -18 cm

From lens makers formula

1/f = (n - 1)(1/18 + 1/18) = (n-1)/9

f = 9/(n-1)

Power, P = 1/f ( in m) = (n-1)/0.09

Now, this lens is in with conjunction with a concave mirror which then can be thought of as to be in conjunction with another thin lens

Power of concave mirror = P' = 1/f ( in m) = 2/R = 2/0.18 = 1/0.09

Net power of the combination = 2P + P' = 2(n-1)/0.09 + 1/0.09 = 1/0.05

n = 1.4

7 0

2 years ago

3. The picture below is an example of a _______ _________ (Answer is 2 words)

makvit [3.9K]

Answer:

it shows examples of types of forces

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3 years ago

1. An electric iron has a rating of 750W, 220V. Calculate:

horrorfan [7]

The equation for electrical power isP=VIwhere V is the voltage and I is the current. This can be rearranged to solve for I in 6(a). 6(b) can be solved with Ohm's LawV=IRor if you'd like, from power, after substituting Ohm's law in for IP=V2R For 7, realize that because they are in parallel, their voltages are the same. We can find the resistance of each lamp fromP=V2RThen the equivalent resistance as1R∗=1R1+1R2Then the total power asPt=V2R∗However, this will reveal that (with a bit of algebra)Pt=P1+P2 For 8, again the resistance can be found asP=V2RThe energy usage is simplyE=P⋅t

6 0

3 years ago