Question

Consider the schematic of the molecule shown, with two hydrogen atoms, H, bonded to an oxygen atom, O. The angle between the two bonds is 106°. If the bond length r = 0.103 nm long, locate the center of mass of the molecule. The mass mH of the hydrogen atom is 1.008 u, and the mass mO of the oxygen atom is 15.9999 u. (Use a coordinate system centered in the oxygen atom, with the x-axis to the right and the y-axis upward. Give the coordinates of the center of mass in nm.)

Answer 1

The definition of the center of mass allows to find the result for the position of the mass center of more than the H₂O molecule is;

         $x_{cm} = 0 \ and \ y_{cm} = 6.9 10^{-3 } nm$  

the concept of center of mass of a system is the point where external forces are applied, it is given by the expression

             $\frac{x}{y} =\frac{1}{M_{total}} \sum m_i r_i$  

Where M is the total mass of the systemr_i and m_i sums the position and masses of the element i of the system

In the attachment we have a diagram of the system where the axis and coordinates of the molecules are shown, in this case it is indicated that the origin is in the oxygen atom, so its distance is zero.

           $r_{cm} = \frac{1}{2 m + M} \ (2 m r )$ )

They indicate the mass of the hydrogen atom m = 1.008 amu, the bond length r = 0.103 nm and there is an angle 106º between the two hydrogens, therefore the angle from the vertical is:

           θ = 106/2 = 53º

Let's find the position of the center of mass for each axis.

x-axis

           $x_{cm} = \frac{1}{2m+ M} \ ( m x_1 - m x_2)$  

y-axis

          $y_{cm} = \frac{1}{2m + M} \ ( m y_1 + m_2)$

Let's use trigonometry to find the components of the bond length.

         cos θ = $\frac{y}{L}$  

         sin θ = $\frac{x}{L}$  

         y = L cos θ

         x = L sin θ  

We substitute.

          $x_{cm} = \frac{1}{2m+M} \ (mL (sin 53 + sin (-53)) \\y_{cm} = \frac{1}{2m + M} \ ( mL cos 53 + mL sin 53)$

we use.  

          sin θ = - sin -θ

          cos θ = cos -θ

Let's calculate.

        $x_{cm} = 0 \\y_{cm} = \frac{1}{2 \ 1.008 + 15.9999} \ ( 2 \ 1.008 \ 0.103 cos 53)$

       

We see that the center of mass is on the x axis and at a distance from the y-axis of 6.9 10-3 nm

In conclusion using the definition of the center of mass we can find the result for the position of the center of mass of the H₂O molecule is;

          $x_{cm}=0$  and $y_{cm}$cm = 6.9 10⁻³ nm

Learn more here: brainly.com/question/8662931