{[ promptMessage ]}

Bookmark it

{[ promptMessage ]}

ENG045_HW.3.SOLNS

# ENG045_HW.3.SOLNS - DATE DUE ENG45 Solution to homework...

This preview shows pages 1–2. Sign up to view the full content.

DATE: October 16, 2011 DUE: October 21, 2011 ENG45, Solution to homework set #3. 1. Weak interactions. We can write the van der Waals’ interaction energy between two atoms separated by the distance r , in the following three ways V ( r ) = 4 E 1 parenleftBigg parenleftbigg σ 1 r parenrightbigg 12 - parenleftbigg σ 1 r parenrightbigg 6 parenrightBigg (1) = E 2 parenleftBigg parenleftbigg σ 2 r parenrightbigg 12 - 2 parenleftbigg σ 2 r parenrightbigg 6 parenrightBigg (2) = K R r 12 - K A r 6 (3) where E 1 and E 2 are energies, σ 1 and σ 2 are distances, and K A and K R are constants with units necessary for the equalities above. a. Determine the SI units of K R and K A such that expression (3) makes sense. If the terms have units of energy (and they do), then we have [ K A ] = [ Jm 6 ] and [ K R ] = [ Jm 12 ] . b. Write the interatomic force F ( r ) associated with the energy expressed in the form (1). F ( r ) = - ∂V ∂r = 24 E 1 σ 1 parenleftBigg 2 parenleftbigg σ 1 r parenrightbigg 13 - parenleftbigg σ 1 r parenrightbigg 7 parenrightBigg (4) c. Write the interatomic force

This preview has intentionally blurred sections. Sign up to view the full version.

View Full Document
This is the end of the preview. Sign up to access the rest of the document.

{[ snackBarMessage ]}

### Page1 / 3

ENG045_HW.3.SOLNS - DATE DUE ENG45 Solution to homework...

This preview shows document pages 1 - 2. Sign up to view the full document.

View Full Document
Ask a homework question - tutors are online