The speed of light in a vacuum is 2.998 × 10 8 8 m/s. How long does it take for light to circumnavigate the Earth, which has a c
1 answer:
Answer:- 0.134 seconds
Solution:- The speed is given as and the circumference is 24900 miles which is same as the distance light have to covered. It asks to calculate the time required to cover this distance by the light.
We need to do unit conversion from miles to meter as the speed is given in meter per second.
1 mile = 1609.34 meter
So,
= 40072566 meters
Know that,
It's rearranged to time as,
Let's plug in the values in it:
= 0.134 seconds
So, the light would take 0.134 seconds to travel the mentioned speed. The answer without the unit is 0.134.
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Explanation :
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Mathematically,
where,
are the initial volume and temperature of the gas.
are the final volume and temperature of the gas.
We are given:
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1. <em>Balancing nuclear equations </em>
Answer:
Explanation:
The main point to remember in balancing nuclear equations is that the <em>sums of the superscripts</em> (the mass numbers) and the <em>subscripts</em> (the nuclear charges) <em>must balance</em>.
Mass numbers: 37 + 0 = 37; balanced.
Charges: 18 + 1 = 17; balanced
B is <em>wrong</em>. Mass numbers not balanced. 6 +2(1) ≠ 4 + 3.
C is <em>wron</em>g. Mass numbers not balanced. 254 + 4 ≠ 258 + 2(1).
D is <em>wron</em>g. Mass numbers not balanced. 14 + 4 ≠ 17 + 2.
===============
2. <em>Amount remaining </em>
Answer:
D. 5.25 g
Explanation:
The half-life of Th-234 (24 da) is the time it takes for half the Th to decay.
After one half-life, half (50 %) of the original amount will remain.
After a second half-life, half of that amount (25 %) will remain, and so on.
We can construct a table as follows:
No. of Fraction Amount
<u>half-lives</u> <u>t/(da</u>) <u>remaining</u> <u>remaining/g</u>
1 24 ½ 21.0
2 48 ¼ 10.5
3 72 ⅛ 5.25
4 96 ¹/₁₆ 2.62
We see that 72 da is three half-lives, and the amount of Th-234 remaining is 5.25 g.
===============
3.<em> Calculating the half-life </em>
Answer:
a. 2.6 min
Explanation:
The fraction of the original mass remaining is 1.0 g/4.0 g ≈ ¼.
We saw from the previous table that it takes two half-lives to decay to ¼ of the original amount.
2 half-lives = 5.2 min Divide both sides by 2
1 half-life = 5.2 min/2 = 2.6 min