Answer:
A sample of 5.2 mg decays to .65 mg or to 1/8 of its original amount.
1/8 = 1/2 * 1/2 * 1/2 or 3 half-lives.
3 * 30.07 = 90 yrs for 5.2 mg to decay to .65 mg
You can get these other numbers similarly:
5.2 / .0102 = 510 requires about 9 half-lives which is 30 * 9 = 270 yrs
Answer:
a) x_{cm} = m₂/ (m₁ + m₂) d
, b) x_{cm} = 52.97 pm
Explanation:
The expression for the center of mass is
= 1 / M ∑ 
Where M is the total masses, mI and xi are the mass and position of each element of the system.
Let's fix our reference system on the oxygen atom and the molecule aligned on the x-axis, let's use index 1 for oxygen and index 2 for carbon
x_{cm} = 1 / (m₁ + m₂) (0+ m₂ x₂)
Let's reduce the magnitudes to the SI system
m₁ = 17 u = 17 1,661 10⁻²⁷ kg = 28,237 10⁻²⁷ kg
m₂ = 12 u = 12 1,661 10⁻²⁷ kg = 19,932 10⁻²⁷ kg
d = 128 pm = 128 10⁻¹² m
The equation for the center of mass is
x_{cm} = m₂/ (m₁ + m₂) d
b) let's calculate the value
x_{cm} = 19.932 10⁻²⁷ /(19.932+ 28.237) 10⁻²⁷ 128 10-12
x_{cm} = 52.97 10⁻¹² m
x_{cm} = 52.97 pm
Answer:
Explanation:
Let x ft be used to make square and 2-x ft be used to make equilateral triangle.
each side of square = x/4
area of square = ( x /4 )²
Each side of triangle
= (2-x) /3
Area of triangle = 1/2 (2-x)²/9 sin 60
= √3 / 36 x (2-x)²
Total area
A = ( x /4 )² +√3 / 36 (2-x)²
For maximum area
dA/dx = 0
1/16( 2x ) -√3 / 36 x2(2-x) = 0
x / 8 - √3(2-x)/ 18 = 0
x / 8 - √3/9 + √3/18 x = 0
x ( 1/8 + √3/18 ) = √3/9
x(.125 +.096 ) = .192
x = .868 ft
Explanation:
acceleration is weight*gravity
tension is the weight In Newtons
Answer:
The frequency of the wheel is the number of revolutions per second:
f= \frac{N_{rev}}{t}= \frac{10}{1 s}=10 Hz
And now we can calculate the angular speed, which is given by:
\omega = 2 \pi f=2 \pi (10 Hz)=62.8 rad/s in the clockwise direction.
Explanation:
