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lorasvet [3.4K]
3 years ago
7

Francium decays with a half-life of 22 minutes. If we start out with 639 mg of francium,how much would remain after 2.7 hours?

Physics
1 answer:
Vinil7 [7]3 years ago
6 0

Answer:

3.87 or 3.9 mg

Explanation:

2.7h * 60mins = 162mins

number of 1/2 lives = 162/22= 7.364

amount remaining = 639(1/2)^7.364 = 3.8796

answer = 3.87 or 3.9

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What would be 1/2 times 800?
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Write 3 – 4 sentences predicting the changes in electrostatic force, strong nuclear force, and the stability of a nucleus if the
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What is the difference between total distance covered vs. total displacement of the rube goldberg
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A girl walks 5km due north,then in the direction of 60° of northeast towards her final destination.If the magnitude of her resul
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Answer:

4.2 km

Explanation:

A triangle is a polygon with three sides and three angles. There are different types of triangles such as isosceles triangle, scalene triangle, equilateral triangle and right angled triangle.

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\frac{a}{sin(A)}=\frac{b}{sin(B)}=\frac{c}{sin(C)}

Let the starting point be A, hence the side opposite to the  angle = a = distance travelled in north east direction.

Let the point of 60° of northeast be B = 90° + (90° - 60°) = 120°, hence the side opposite to the  angle = b = resultant displacement = 8 km.

Let C be the endpoint, hence the side opposite to the  angle = c = distance travelled north = 5 km

Using sine rule:

\frac{b}{sin(B)}=\frac{c}{sin(C)}  \\\\\frac{8}{sin(120)}=\frac{5}{sin(C)}  \\\\sin(C)=\frac{5*sin(120)}{8} =0.5412\\\\C=sin^{-1}(0.5412)=32.8^o\\\\

∠A + ∠B + ∠C = 180° (sum of angle in a triangle)

∠A + 120 + 32.8 = 180

∠A = 27.2°

\frac{b}{sin(B)}=\frac{a}{sin(A)}  \\\\\frac{8}{sin(120)}=\frac{a}{sin(27.2)}  \\\\a=\frac{8*sin(27.2)}{sin(120)} \\\\a=4.2\ km

Therefore she travelled 4.2 km in the north east direction

5 0
3 years ago
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