Exploratorium

=__Collisions and Momentum__= toc
 * Choose topic… on 4/19/12
 * Complete presentation date availability survey… by 5/6/12
 * Recruit assistants, if desired… by 5/12/12
 * Set up and Background research: plan/proposal/research 5/16/12
 * Gather materials 5/19/12
 * First attempt of demo #1-4 5/23/12
 * First draft written script 5/25/12
 * Trifold poster plan/sketch/draft 1 5/26/12
 * Written list of needed materials 5/27/12
 * Gather all needed materials 5/29/12
 * Second draft written script 5/30/12
 * Trifold poster draft 2 5/31/12
 * Practice 2 demos # 1 – 4 6/3/12
 * Trifold poster final draft 6/4/12
 * Practice 3 demos # 1 – 4 6/5/12
 * Dress Rehearsal 1… TBA
 * Final draft written script 6/8/12
 * Dress Rehearsal 2… TBA
 * Show… TBA

= Proposal: = My topic for the Exploratorium Demo is momentum and collision. The demos that I will be doing are the Double Ball Bounce, Newton's Cradle, Dominoes, and Exploding Carts. My takeaway demo will be the Double Ball Bounce. I will be able to explain these demos to the students in simplified terms and help them gain a basic understanding of momentum and collisions.

=** Demos: **=

Double Ball Bounce: Takeaway demo Newton's Cradle Dominoes Exploding Carts

=** Materials: **=

Double Ball Bounce: 1 Basketball 1 Tennis ball Numerous smaller bouncy balls of a similar size proportion (such as a tennis ball and a small bouncy ball) as the takeaway Numerous small dowels to go along with the smaller ball sets Are you purchasing these items?

Newton's Cradle: 1 Newton’s Cradle

Dominoes: 1 Set of Dominoes

Exploding Carts: 1 Set Scooter Carts

=** Procedure: **=

Double Ball Bounce

Newton’s Cradle: Lift up one ball and release it to start the Newton’s cradle going. After a few times back and forth, I will ask the kids why this works and then explain.

Dominoes

Exploding Carts

= Script: =

Exploratorium:

Eric: Welcome to our Physics Demonstration

Rob: What is physics you may ask yourselves? Physics is work. Physics is energy. Physics is why things happen.

KosMuffin: What we are here to talk about today specifically is the physics of collisions and momentum.

Remzi: Does anybody know what we mean by this? What is a collision?


 * Ask kids**

Eric: Well basically, collisions are when two objects crash into one another. How they crash is determined by their momentum. Take these scooter carts, for example. Remzi and Rob here are going to get on these scooters.

Remzi: So we are going to sit down on these scooters. Now, we are going to place our hands out like this **(place hands out onto Rob's)**.

Rob: Next, we are going to push off of one another **(push off)**. This called an exploding collision. No, I don't mean like a fiery bomb exploding. What an exploding collision means is that two objects are colliding outwards instead of into one another

Remzi: Now we are going to do this again. Except for this time, I want you to pay attention to something. Hey Rob, how much do you weigh?

Rob: **(says weight)**. Hey Remzi, how much do you weigh?

Remzi: **(says weight)**. Now do you see that I am heavier than Rob. So if we push off of each other with equal strength, what do you think will happen if we push off of each other with equal strength? THE KIDS WILL WANT TO DO THIS! And I think it would be great demonstration to show such a big discrepancy in masses.


 * Ask kids**

Rob: When we do this, I should move further and faster than Remzi moves. This is because of the Law of Conservation of Momentum. Since I am smaller than Remzi, I should move faster. And since he is larger than me, he should move slower. This shows that collisions depend upon mass, which is similar to weight, as well as velocity, which is similar to speed.

Kosuke: All right, now we are going to play with some toys. Have any of you ever played with dominoes? **(pause for reaction)** Now I love playing with dominoes, but does anyone else think of physics when playing with dominoes? I do. Now watch this **(knocks down set of two dominoes)**. Did you see why that involves physics? You see, when the domino falls, it spins in a circular pattern while falling, like this **(demonstrates how a domino falls with arm)**. The domino falling creates momentum for the domino. And then, at a certain point, the first domino hits another one. This is the collision. And this causes the next domino to lose its balance and fall in a circular pattern, just like the first domino. Now, lets try this with a few more dominoes. Would someone like to push the first on over?


 * Volunteer from the crowd**

Eric: So now we have seen two examples of how momentum from one object can cause other objects to move. Has anyone ever seen something like this over here (points to Newton's Cradle)? How this works is I lift up one metal ball. I then drop it and allow it to swing down. A metal ball on the other side should rise up to around the same height that I dropped the first ball from. This process will continue for a while. Now let's try this out.


 * Do demo**

The reason why this works is because the first ball transfers its energy and momentum to the second ball, and to the third ball, until it reaches the last one. Since the last ball has all that momentum and nothing to hit, it swings up and then gravity pulls it back down. And that continues on and on, until friction and energy loss due to heat slows it down. What do you think will happen if I do this while lifting two balls up **(tries again with two)**? Now how about three **(tries with three)**? Four **(tries with four)**? Five **(tries with five)**?

In order to make it so that there are equal masses and equal velocities, we need to have the same number of balls leaving as there are entering

Eric: Now here comes the last demo. This is called the double ball bounce. Before we explain anything, just watch.


 * Drops the balls**

Kosuke: Now, why did the tennis ball go flying? Anyone have any idea?


 * Asks kids**

Rob: Well you can see that the basketball is much larger, and more importantly, heavier than the tennis ball. I would say that the basketball is at least three times the weight of the tennis ball. So when the basketball is dropped, it hits the ground slightly before the tennis ball collides with the basketball. The basketball begins to move upwards. A nd because of the Law of Conservation of Momentum, which we discussed earlier, You should just restate the point... they aren't going to remember and/or the connection may not be obvious the tennis ball is sent flying upwards with a much larger velocity than the basketball. This makes the tennis ball fly to at least 9x the height of the original drop.

Remzi: So let’s make some of these double ball bounces **(hands out materials)**.

First, take the dowel and put it inside the little hole in the tennis ball. Then put the other end on the bouncy ball. Then drop the tennis ball and see the bouncy ball pop off. Try dropping with the bouncy ball on top, or at different angles.

Eric: Alright, that concludes our demo today. Thanks for listening and go explore some more physics.