We took a car and rolled it down a ramp into the wall. We then measured the amount that it bounced back off the wall. Next, we made a cushion that would increase the time it took for the collision to occur. We placed the cushion on the wall, rolled the car down the ramp again and then measured the bounce back with the cushion. This is in an 8th grade middle school science class. We studied Newton's 3rd law, force-pairs, and we know that we need to increase the time in the implulse to decrease the force of the collision. Our goal is to have the car experience less force in the collision so it is safer for passengers. We related this to the real-world applications of airbags and crumple zones on cars. The question is: for our cushion to be effective, do we want to have MORE bounce back or less bounce back? I was assuming that having a cushion would reduce the bounce back by absorbing some of the momentum, but the examples given by the district show that the bumper car with more bounce back is safer than a car hitting a brick wall and coming to a complete stop really fast, so it seems like more bounce is better. When our test car bounced off the wall it bounced back an average of 85 cm. Most students are getting less bounce back with cushions than the control runs without.
I have also seen air drops where the delievered item is surrounded by bouncy material to protect it and it makes sense that more bounce is better than a crash landing. How can we talk about the amount of bounce back correctly in terms of Newton's 3rd law and collisions with and without a cushion. Please help, I'm the teacher ;)