• Support PF! Buy your school textbooks, materials and every day products Here!

Molecule Kinetics

  • Thread starter bpw91284
  • Start date
  • #1
67
0

Homework Statement



A space vehicle returning from the Moon enters Earth’s atmosphere at a speed of about 4.9E4 km/h. Molecules (assum nitrogen) striking the nose of the vehicle with this speed correspond to what temperature?

Homework Equations



KE=0.5mv^2=kT
k: constant

The Attempt at a Solution



I'm lost.
 

Answers and Replies

  • #2
Dick
Science Advisor
Homework Helper
26,258
618
Look up the mass of an N2 molecule and Boltzmann's constant, k, put them into your first equation and solve for T. ????
 
  • #3
67
0
Look up the mass of an N2 molecule and Boltzmann's constant, k, put them into your first equation and solve for T. ????
Can't look up mass, only molecular weight. Where mass=#mols*molecular weight.
 
  • #4
Dick
Science Advisor
Homework Helper
26,258
618
Can't look up mass, only molecular weight. Where mass=#mols*molecular weight.
You can so look up the mass of a single nitrogen atom. It's in the periodic table in atomic mass units. What's an atomic mass unit in kilograms? Can also be looked up.
 
  • #5
67
0
You can so look up the mass of a single nitrogen atom. It's in the periodic table in atomic mass units. What's an atomic mass unit in kilograms? Can also be looked up.
N=14.00674u
1 u ≈ 1.66053886 × 10−27 kg

Then just solve for T with 0.5mv^2=kT?

Thanks,
Brandon
 
  • #6
Dick
Science Advisor
Homework Helper
26,258
618
Except remember the question says 'molecules' and nitrogen is N2 (two nitrogen atoms).
 
Last edited:

Related Threads on Molecule Kinetics

  • Last Post
Replies
4
Views
53K
Replies
3
Views
858
Replies
2
Views
2K
Replies
1
Views
6K
Replies
13
Views
1K
Replies
9
Views
5K
Replies
1
Views
5K
Replies
3
Views
699
Replies
1
Views
699
Replies
1
Views
4K
Top