1. The document provides instructions for a lab on crumple zones. Students will design and test crumple zones made of paper, tape, rubber bands and string to protect a block in a cart from tipping over during crashes. 2. The document discusses factors that must be considered when designing crumple zones like materials and how cushioning can be described scientifically as increasing stopping distance or time. 3. Formulas are provided that show as distance or time increase during impact, force decreases, helping to decrease the risk of injury in a collision.

2. Good Morning!Today we will:conduct an investigationtake some notescomplete a success criteria checkPlease do before the bell:get your lab notebookget out something to write withget a textbook and open to page 321

3. What Do You See?

4. Lab: Crumple ZonesMake a new entry in your lab book. Title it, “Impulse and Changes in Momentum: Crumple Zone”Be sure to make the corresponding entry in your Table of Contents

5. Read pages 321 - 322We will be doing Part A of the lab today. While reading about it, pay special attention to:materials you will usewhat you will be doing/investigating3 minutes

6. Crumple ZonesWhat are some of the factors that automobile designers and engineers must consider when designing a crumple zone as a safety feature?1:2:4: Copy this question down in your lab book and jot down your ideas2 minutes

7. Crumple ZonesShare your ideas with your table partner; add anything to your list that you think of while discussing with your partner2 minNow share with the table behind/in front of you2 min

8. Lab: Crumple ZonesIn this lab, your group will design what it thinks will be the best crumple zone – you will be given one sheet of paper, 30 cm of tape, 2 rubber bands, and 30 cm of string with which to do so.

9. Lab: Crumple ZonesSet up your ramp, cart, block and books (you can also use the wall) as shown in the picture. Test your set-up to be sure that the car will successfully roll down the ramp and crash into the books/wall.5 minutes

10. Lab: Crumple ZonesIn your lab group, discuss, design, and attach your crumple zone to the cart. Your goal: design a crumple zone that will keep the block from tipping over from ramp heights greater than 15 cm.Diagram your design in your lab notebook. Be sure to label your design!12 minutes

11. Lab Debrief: What works, what doesn’t?The tape doesn’t help hold the block in place when the cart crashes. Why?

12. Forces Affecting CollisionsThe goal of a crumple zone is to add “cushioning.” How can we describe cushioning in scientific language?cushioning = increased stopping distance

13. cushioning = increased stopping timeThe Math of Increased Stopping DistanceWe already know:work done = force x distancework done = ΔKEFrom these relationships, we get:ΔKE = force x distanceWe call this the Kinetic Energy – Work Theorem

14. ΔKE = force x distanceLooking at that relationship between the change in kinetic energy, force and distance, keep something in mind:An object in motion has a “set” kinetic energy: it is a factor of its mass and its velocity. To change that kinetic energy, work (force x distance) must be done.

15. ΔKE = force x distanceSo, for a given kinetic energy, what happens to force as distance is increased?as distance increases, force decreases

16. The Math of Increased Stopping TimeInstead of focusing on the distance over which a force acts, we can focus on the amount of time over which a force acts.We already know:Ft = ΔmomentumAnd just like with kinetic energy, the momentum an object has is “set” for a given situation.

17. Ft = ΔmvSo if the Δmv is set (say from 1000 kgm/s to zero kgm/s), what happens to force as time is increased?as time in increased, force is decreased

18. Impulse = Change in MomentumWhat would this relationship look like in a formula?Ft = ΔmvThe change in momentum is called impulse

19. Work & Energy? Or Impulse & Momentum?EITHER!The work-energy theorem and the impulse-momentum theorem both describe the effect of “cushioning.”As a student, it is you job to figure out which relationship is more appropriate to use given what you know about a situation.

20. Designing a Safer VehicleDesigning a safety device for a vehicle is often centered around finding ways to decrease the force and increase the time/distance of an impact.