answer key

ANSWER KEY 1. Why did the dummy get left behind? Because it has inertia and a body at rest wants to stay at rest. 2. How can we prevent the crash test dummy from slamming its head into the windshield? By making sure that we secure it with a seatbelt 3. What does the ∆ (delta) symbol mean in the equations mentioned in the video? It means the change in something 4. Momentum is ____energy_____ in motion. 5. What is the formula for momentum? Momentum = Mass · Velocity P=m·v 6. What changes an objects momentum & what is the formula for this? Impulse changes an objects momentum and the formula is Force · Time J = F · ∆t J = ∆P 7. List at least 2 observations about the two red cars coming to a stop. • The impulse required to stop the cars is equal. • The car that applied less braking force took a longer distance and time to come to a stop. • The car that panic brakes lurches forward more. • The body of the person that panic braked wants to continue moving forward. • The body of the person that braked slowly seemed unaffected by the slowing. 8. Why are “crumple zones” important and how do they help to keep you safe? Because these areas increase the amount of time that it takes for the force of the crash to be dispersed and therefore decreasing the amount of force that is inflicted upon you. 9. If you are in a car crash is it better to be in a car with greater mass or less mass? (circle one) 10. Where do we want to focus the damage of a car crash and why? We want to focus the damage into the frame of the car. 11. Why do you have less protection during an impact from the side of a car vs. the front of the car? Because there is less material available to reduce the force of the impact and increase the time of the impact. 12. Do you typically wear a seatbelt when you’re in a car, regardless of where you are riding in the car? BE HONEST! 13. If not, do you think that you’re more likely to wear one now that you understand the physics behind them?