Astronomers are comparing two stars that are known to have the

Which of the following scenarios would be optimal for obtaining a date from radioactive decay using these isotopes: 87Rb, 147Sm,

REY [17]

Answer:

a) 238U, 40K and 87Rb, b) 235U and to a lesser extent 40K , c) he 235U,

d) possibility is 14C , e)this period would be ideal for 14C , f) 14C should be used since it is the one with the least average life time, even though the measurements must be very careful

Explanation:

One of the applications of radioactive decay is the dating of different systems.

To do this, the quantity of radioactive material in a meter is determined and with the average life time, the time of the sample is found.

Let's write the half-life times of the given materials

87Rb T ½ = 4.75 1010 years

147Sm T ½ = 1.06 1011 years

235U = 7,038 108 years

238U = 4.47 109 years

40K = 1,248 109 years

14C = 5,568 103 years

we already have the half-life of the different elements given

a) meteors. As these decomposed in the formation of the solar system, their life time is around 3 109 to 5 109 years, so it is necessary to look for elements that have a life time of this order, among the candidates we have 238U, 40K and 87Rb if these elements were at the moment of the formation of these meteors, there must still be rations in them, instead elements 14C already completely adequate

b) rock. The formation period is 4.20-108 years, therefore one of the most promising elements is 235U and to a lesser extent 40K since it is more abundant in rocks. The other elements with higher life times have not decayed and therefore will not give a true value and the 14C is completely decayed

c) volcanic ash. Formation time 6107 years, the only element that has the possibility of having a count is the 235U, the others have a life time so long that they have not decayed and the 14C is complete, unbent

d) scarp of an earthquake formation time 5 101 years, The only one that has any possibility is 14C even when it has declined very little, all the others, you have time to long that has not decayed

e) INCA excavation. The time of this civilization is about 10000 to 500 years (104 to 5 102 years), we see that this period would be ideal for 14C since it has some period of cementation, the others have not decayed

f) Tree in Blepharitis. 14C should be used since it is the one with the least average life time, even though the measurements must be very careful because of a period of disintegration. We have such a long time that they have not decayed

8 0

4 years ago

A 200g piece of iron is heated at 100C. It is than dropped into water to bring its temperature down to 22C. What is the amount o

gizmo_the_mogwai [7]

Answer:

6926.4J

Explanation:

Given parameters:

Mass of iron = 200g

Initial temperature = 100°C

Final temperature = 22°C

Unknown:

Amount of heat transferred to the water = ?

Solution:

The quantity of heat transferred to the water is a function of mass and temperature of the iron;

H = m c Ф

m is the mass of the iron

Ф is the change in temperature

C is the specific heat capacity of iron = 0.444 J/g°C

Now;

insert the parameters and solve;

H = 200 x 0.444 x (100-22)

H = 6926.4J

8 0

3 years ago

A point charge is used to determine the electric field around a charged particle. Why is it necessary that the point charge does

Mnenie [13.5K]

The strength, and possibly the shape and direction, of the electric field
around a charged particle depends on the location of the particle.

If the process of measuring the field causes the particle to move, then
the measurement you get wouldn't mean anything.

Your measurements wouldn't show the ACTUAL field around the particle.
They would show what the field is like AFTER something comes along
and distorts it, and that's not what you're trying to measure.

It would be like carrying a flame thrower into a freezer when you go in
to measure the temperature in there.

Or if you had to measure how much light is leaking into a dark room,
and you carried a flashlight with you to see your way around in there.

7 0

3 years ago

The velocity function (in meters per second) for a particle moving along a line is given by v(t) = t³ - 15t². Find the displacem

Sonbull [250]

Answer:

Total displacement will be 1120 meters.

Explanation:

To calculate displacement from the velocity, need to take integral of velocity for a one time period.

$x=\int\limits^7_{-1} {t^3-15*t^2} \, dt\\x=\int\limits^7_{-1} {t^3} \, dt-\int\limits^7_{-1} {15*t^2} \, dt\\x=600-1720\\x=-1120$

The total displacement is 1120 meter in negative way.

4 0

4 years ago

How can you use Newton's second law to find force

Citrus2011 [14]

Newton's second law is F = ma where F is force, m is mass, and a is acceleration. If you know the mass and acceleration of an object you can find it's force using his formula.

3 0

3 years ago