# Lecture9 - PHYSICS 231 INTRODUCTORY PHYSICS I Lecture 9...

This preview shows pages 1–8. Sign up to view the full content.

PHYSICS 231 INTRODUCTORY PHYSICS I Lecture 9

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

View Full Document
Momentum: Newton’s 2 nd : Conserved for isolated objects Useful for short times Collisions (p always conserved) Elastic (E conserved too) Inelastic (E not conserved) Last Lecture r p = m r v r F = " r p " t Impulse = F ! t = ! p
Example 6.7 A proton (m p =1.67x10 -27 kg) elastically collides with a target proton which then moves straight forward. If the initial velocity of the projectile proton is 3.0x10 6 m/s, and the target proton bounces forward, what are a) the final velocity of the projectile proton? b) the final velocity of the target proton? 0.0 3.0x10 6 m/s

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

View Full Document
Elastic collision in 1-dimension 1. Conservation of Energy: 2. Conservation of Momentum: Rearrange both equations and divide: 1 2 m 1 v 1 i 2 + 1 2 m 2 v 2 i 2 = 1 2 m 1 v 1 f 2 + 1 2 m 2 v 2 f 2 (1) m 1 v 1 i + m 2 v 2 i = m 1 v 1 f + m 2 v 2 f (2) m 1 v 1 i 2 " v 1 f 2 ( ) = m 2 v 2 f 2 " v 2 i 2 ( ) (1) m 1 v 1 i " v 1 f ( ) v 1 i + v 1 f ( ) = m 2 v 2 f " v 2 i ( ) v 2 f + v 2 i ( ) m 1 v 1 i " v 1 f ( ) = m 2 v 2 f " v 2 i ( ) (2) v 1 i + v 1 f = v 2 f + v 2 i " v 1 i # v 2 i = # v 1 f # v 2 f ( )
Elastic collision in 1-dimension Final equations for head-on elastic collision: Relative velocity changes sign Equivalent to Conservation of Energy m 1 v 1 i + m 2 v 2 i = m 1 v 1 f + m 2 v 2 f v 1 i " v 2 i = " v 1 f " v 2 f ( )

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

View Full Document
Example 6.8 An proton (m p =1.67x10 -27 kg) elastically collides with a target deuteron (m D =2m p ) which then moves straight forward. If the initial velocity of the projectile proton is 3.0x10 6 m/s, and the target deuteron bounces forward, what are a) the final velocity of the projectile proton? b) the final velocity of the target deuteron? v p =-1.0x10 6 m/s v d = 2.0x10 6 m/s Head-on collisions with heavier objects always lead to reflections
The mass M 1 enters from the left with velocity v 0 and strikes the mass M 2 =M 1 which is initially at rest. The collision is perfectly elastic. a) Just after the collision v

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 / 37

Lecture9 - PHYSICS 231 INTRODUCTORY PHYSICS I Lecture 9...

This preview shows document pages 1 - 8. Sign up to view the full document.

View Full Document
Ask a homework question - tutors are online