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3 years ago

The ease with which a material allows electricity to move is called

Physics

2 answers:

Mkey [24]3 years ago

6 0

The ease with which a material allows electricity to move is called

C. CONDUCTIVITY

ivann1987 [24]3 years ago

4 0

Answer:

C. conductivity.

Explanation:

Conductivity measures the capacity of a material to allow electrical current to pass through it. This property depends on the physical factors, the temperature and the atomic structure of the material. For example, metals are good conductors because they have many electrons in the conduction band, that is, weakly attached to their nuclei, which allows a large flow of them.

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nordsb [41]

A) 320 count/min

B) 40 count/min

C) 80 count/min, 11400 years

Explanation:

The activity of a radioactive sample is the number of decays per second in the sample.

The activity of a sample is therefore directly proportional to the number of nuclei in the sample:

$A\propto N$

where A is the activity and N the number of nuclei.

As a consequence, since the number of nuclei is proportional to the mass of the sample, the activity is also directly proportional to the mass of the sample:

$A\propto m$

where m is the mass of the sample.

In this problem:

- When the mass is $m_1 = 1 g$ , the activity is $A_1=16 count/min$

- When the mass is $m_2=20 g$ , the activity is $A_2$

So we can find A2 by using the rule of three:

$\frac{A_1}{m_1}=\frac{A_2}{m_2}\\A_2=A_1 \frac{m_2}{m_1}=(16)\frac{20}{1}=320 count/min$

The equation describing the activity of a radioactive sample as a function of time is:

$A(t)= A_0 e^{-\lambda t}$ (1)

where

$A_0$ is the initial activity at time t = 0

t is the time

$\lambda$ is the decay constant, which gives the probability of decay

The decay constant can be found using the equation

$\lambda = \frac{ln2}{t_{1/2}}$

where $t_{1/2}$ is the half-life, which is the amount of time it takes for the radioactive sample to halve its activity.

In this problem, carbon-14 has half-life of

$t_{1/2}=5700 y$

So its decay constant is

$\lambda=\frac{ln2}{5700}=1.22\cdot 10^{-4} y^{-1}$

We also know that the tree died

t = 17,100 years ago

and that the initial activity was

$A_0 = 320 count/min$ (value calculated in part A, corresponding to a mass of 20 g)

So, substituting into eq(1), we find the new activity:

$A(17,100) = (320)e^{-(1.22\cdot 10^{-4})(17,100)}=40 count/min$

We know that a sample of living wood has an activity of

$A=16 count/min$ per 1 g of mass.

Here we have 5 g of mass, therefore the activity of the sample when it was living was:

$A_0 = A\cdot 5 = (16)(5)=80 count/min$

Moreover, here we have a sample of 5 g, with current activity of $A=20 count/min$ : it means that its activity per gram of mass is

$A'=\frac{20}{5}=4 count/min$

We know that the activity halves after every half-life: Here the activity has became 1/4 of the original value, this means that 2 half-lives have passed, because:

- After 1 half-life, the activity drops from 16 count/min to 8 count/min

- After 2 half-lives, the activity dropd to 4 count/min

So the age of the wood is equal to 2 half-lives, which is:

$t=2t_{1/2}=2(5700)=11,400 y$

3 0

4 years ago

What is the acceleration caused by gravity of the planet Earth?

Luda [366]

The general accepted value of acceleration due to gravity, g, is 9.81 m/s^2.

That is an approximation because being the acceleration of gravity due to the attraction of the earth its magnitude will depend on the distance from the point to the center of the planet Earth.

The value of g is determined by using the Newton's Universal Law of gravity:

F = G * m of Earth * m of body / (distance^2)

Wehre {G* m of Earth / (distance^2) } = g

G is a universal constant = 6.67 * 10 ^ -11 N*m^2 / kg^2

m of Earth = 5.98 * 10 ^ 24 kg

distance = radius of Earth + height of the body

Given the the Earth is not a perfect sphere the radius varies. Also the height of the body varies.

If you take a mean radius of Earth of 6.37*10^6 m

you get

g = 6.67*10^-11 N*m^2/kg^2 * 5.98*10^24kg / (6.37*10^6 m)^2 = 9.83 m/s^2

Again, if you want a more precise value of g, you need to find the exact place where you are and then use the right r.

7 0

3 years ago

A ball of mass 0.10 kg moving at a speed of 3.0 m/s collides with a wall and bounces directly back with the same speed. If the b

alexdok [17]

The magnitude of the average force exerted on the ball by the wall is calculated below.

The average force exerted by the ball on the wall is 3 N

Explanation:

Given:

mass of the ball (m)=0.10 kg

speed (v) =3.0 m/s

time taken(t) =0.01 seconds

To calculate:

Average force(F) exerted by ball on the wall

We know;

F=(m×v)÷t

F=(0.10×3.0)÷0.01

Therefore the average force exerted by the ball on the wall is 3 N

8 0

4 years ago

The earth's radius is 6.37×106m; it rotates once every 24 hours.What is the speed of a point on the earth's surface located at 3

bagirrra123 [75]

Answer:

v = 120 m/s

Explanation:

We are given;

earth's radius; r = 6.37 × 10^(6) m

Angular speed; ω = 2π/(24 × 3600) = 7.27 × 10^(-5) rad/s

Now, we want to find the speed of a point on the earth's surface located at 3/4 of the length of the arc between the equator and the pole, measured from equator.

The angle will be;

θ = ¾ × 90

θ = 67.5

¾ is multiplied by 90° because the angular distance from the pole is 90 degrees.

The speed of a point on the earth's surface located at 3/4 of the length of the arc between the equator and the pole, measured from equator will be:

v = r(cos θ) × ω

v = 6.37 × 10^(6) × cos 67.5 × 7.27 × 10^(-5)

v = 117.22 m/s

Approximation to 2 sig. figures gives;

v = 120 m/s

8 0

3 years ago

Your family just moved into a new house. There are three rooms available for you, your brother and sister, but one is larger tha

vazorg [7]

Answer:

Competition/collaborate most likely collaboration

Explanation:

Trust me on this this will be the best and least messy way to handle the problem, first try to see if your sister can give away some of her clothes, does your brother really need the room, and can you find a different place to store your drum set if not, competition. Decide a fair competition, something that no one is better at than the other, decide the rules, no cheating, and whatever the out come try to be mature about it, maybe your parents will reward you and your siblings.

8 0

3 years ago