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3 years ago

What is the difference between relative time and absolute time?

1 answer:

7 0

Relative time is the physical subdivision of the rocks found in the Earth's geology and the time and order of events they represent. Absolute time is the measurement taken from the same rocks to determine the amount of time that has expired

Explanation:

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Strontium−90 is one of the products of the fission of uranium−235. This strontium isotope is radioactive, with a half-life of 28

Ludmilka [50]

Answer : The time passed in years is 20.7 years.

Explanation :

Half-life = 28.1 years

First we have to calculate the rate constant, we use the formula :

$k=\frac{0.693}{t_{1/2}}$

$k=\frac{0.693}{28.1\text{ years}}$

$k=2.47\times 10^{-2}\text{ years}^{-1}$

Now we have to calculate the time passed.

Expression for rate law for first order kinetics is given by:

$t=\frac{2.303}{k}\log\frac{a}{a-x}$

where,

k = rate constant = $2.47\times 10^{-2}\text{ years}^{-1}$

t = time passed by the sample = ?

a = initial amount of the reactant = 1.00 g

a - x = amount left after decay process = 0.600 g

Now put all the given values in above equation, we get

$t=\frac{2.303}{2.47\times 10^{-2}}\log\frac{1.00}{0.600}$

$t=20.7\text{ years}$

Therefore, the time passed in years is 20.7 years.

8 0

3 years ago

Skid Marx set the world record for acceleration as he went from zero to 10 m/s in 3 seconds. How far did he travel in that time?

iren [92.7K]

Answer:

12000 miles per hour

Explanation:

If skid Marx went from zero to 10 miles in 3 seconds the his speed would have been 12000 miles per hour.

8 0

3 years ago

The total negative charge on the electrons in 1mol of helium (atomic number 2, molar mass 4) is ________?

DaniilM [7]

Answer:

$1.92\times 10^5 C$

Explanation:

We are given that

Atomic number=2

We have to find the total negative charge on the electrons in one mole of Helium.

We know that atomic number=Proton number

Proton number=Number of electrons=2

Number of electrons in Helium=2

1 mole of Helium= $6.02\times 10^{23}$ atoms

We know that q=ne

Where n =Number of fundamental units

e=Charge on electron

1 e= $1.6\times 10^{-19}C$

Using the formula

$q=2\times 1.6\times 10^{-19}=3.2\times 10^{-19}C$

Total negative charge in 1 mole= $3.2\times 10^{-19}\times 6.02\times 10^{23}=1.92\times 10^5C$

Hence, the total negative charge on the electrons in 1 mole of Helium= $1.92\times 10^5 C$

4 0

3 years ago

If a food has 200 calories and 7 grams of protein, and each gram of protein is 4 calories, what percent of the serving comes fro

poizon [28]

Answer: 13%

Explanation: The reason this is 13 is because you can eat carlories and you can also be an amazing person 200 calories and 7 grams

4 0

1 year ago

A spring-loaded gun can fire a projectile to a height h if it is fired straight up. if the same gun is pointed at an angle of 45

Naily [24]

When firing straight up:
v^2 = u^2 - 2gh, where v = final velocity = 0, u = initial velocity, g = gravitational acceleration, h = maximum height attained.

Then,
0 = u^2 - 2gh
u = Sqrt (2gh) ---- (1)

When firing at 45°,
Initial velocity, U = u Sin 45 = Sqrt (2gh)·Sin 45

Maximum height, H = U^2*(Sin Ф)^2/2g

substituting;
H = [Sqrt (2gh)·Sin 45]^2*(Sin 45)^2]/2g
H = [2gh*(Sin 45)^2*(Sin 45)^2]/2g
H = [h*(Sin 45)^4] = h/4

Therefore, maximum height when the gun fires at 45° is a quarter of maximum height when the gun fires vertically up.

6 0

3 years ago