# Elastic and Inelastic Collisions

In this agenda, Mr. Richter's class will cover the topic of collisions in physics. They will start the lesson by reviewing the homework from section 7.1 and practicing problems for section

## About Elastic and Inelastic Collisions

PowerPoint presentation about 'Elastic and Inelastic Collisions'. This presentation describes the topic on In this agenda, Mr. Richter's class will cover the topic of collisions in physics. They will start the lesson by reviewing the homework from section 7.1 and practicing problems for section. The key topics included in this slideshow are . Download this presentation absolutely free.

## Presentation Transcript

Slide16.3 Elastic and Inelastic CollisionsDate, Section, Pages, etc. Mr. Richter

Slide2Agenda Today:  Warm Up  Review HW from 7.1  Practice Problems for 7.2  Intro to Collisions (7.3)  Tomorrow  Conservation of Momentum Lab  Thursday:  Review HW from 7.2  Finish Collisions (7.3)  Friday:  Problem Solving Practice  Monday:  Concepts Review  Tuesday  Chapter 6 Test

Slide3Warm-Up: Assume two cars have the same mass and speed going into a collision.  Scenario A:  Two cars collide with each other but bounce off.  Neither of them sustain noticeable damage.  Scenario B:  Two cars collide with each other and crumple, sticking together after the crash. 1. In which scenario do you think energy is conserved? 2. In which scenario do you think the driver feels more force?

Slide4Conservation of MomentumPractice Problems

Slide5Practice Problems1. Recoil:  A boy on a skateboard initially at rest tosses an 8.0 kg jug of water in the forward direction at a speed of 3.0 m/s.  If the boy and the skateboard move backward at 0.60 m/s, find the mass of the boy. 2. Collision:  p. 234 #39  As long as everything is in grams (g) and centimeters per second (cm/s), THERE IS NO NEED TO CONVERT.

Slide6Agenda Review HW from 6.2  Recap Elastic and Inelastic Collisions  Problem Solving with Elastic and Inelastic Collisions  Forces in Elastic and Inelastic Collisions

Slide7Objectives Identify different types of collisions.  Calculate change in kinetic energy (or lack thereof) in different types of collisions.  Find the final velocity of objects in different types of collisions.  Understand the relationship between the type of collision and the force experienced by the object.

Slide8Elastic Collisions

Slide9Collisions Collisions can be categorized into two types:  elastic  inelastic  Elastic  collisions are when objects bounce off of each other.  (Elastics are like rubber bands, and rubber bounces)  Scenario A.  Inelastic  collisions are when objects stick together  after the crash.  Scenario B.

Slide10Elastic Collisions In  perfectly  elastic collisions objects:  Bounce off  each other  No loss of energy due to speed (kinetic energy)  No change of shape.  In real life, there are almost no perfectly elastic collisions.  Almost always, some energy is lost to sound or heat  in a collision.

Slide12Elastic Collisions:  Problem Solving Both momentum and kinetic energy are conserved  in perfectly elastic collisions.   Masses separate  afterward.

Slide13Practice Problem

Slide14Inelastic Collisions

Slide15Inelastic Collisions In inelastic collisions objects:  Stay stuck together  Kinetic energy is lost  to:  Primarily internal energy  Heat  Sound  Objects are deformed  (shape is changed.  In real life, most collisions are a combination of elastic and inelastic collisions.  Objects will deform a little, and separate a little.

Slide17Inelastic Collisions:  Problem Solving Only momentum is conserved  in inelastic collisions.   Kinetic energy is lost.  Masses stick together  afterward.

Slide18Practice Problem

Slide19Forces in Collisions

Slide20Forces in Collisions Assume two objects that have the same mass and the same speed collide with each other.  In which type of collision do they experience a greater change in momentum?  inelastic (both vehicles stop)  elastic (both vehicles stop and reverse direction)  Elastic collisions have greater changes in speed, thus the objects experience more force!

Slide21Forces in Collisions: Examples Think of a batter in baseball.  Does the baseball experience more force when the batter:  bunts (inelastic)  hits a home run (elastic)  Your car is designed to crumple (inelastic), so that you experience less force.  Greater changes in momentum mean more force.  Elastic collisions are more forceful!

Slide22Wrap-Up:  Did we meet our objectives? Identify different types of collisions.  Calculate change in kinetic energy (or lack thereof) in different types of collisions.  Find the final velocity of objects in different types of collisions.  Understand the relationship between the type of collision and the force experienced by the object.

Slide23Homework p. 230 #1-5