Last week, we talked about Newton’s Second Law of Motion and the week before, we talked about Newton’s First Law of Motion. If you missed these, check them out at http://discoveryexpress.weebly.com/homeblog/demonstrating-the-law-of-inertia and http://discoveryexpress.weebly.com/homeblog/newtons-second-law.
Newton’s First Law of Motion
An object in motion will stay in motion, or an object at rest will stay at rest, unless affected by an outside force.
Newton’s Second Law of Motion
The acceleration of an object--as produced by a net force--is directly proportional to the magnitude of the net force, in the same direction as the net force, and inversely proportional to the mass of the object. F = m * a
Now that you have revisited Newton’s first two laws, let’s move on to our focus for today, Newton’s Third Law of Motion.
Newton’s Third Law is concerned with forces acting in pairs. Remember, a force is a push or a pull that is enacted upon an object. Forces result from interactions between two objects. For every action force, there is a reaction force.
Another example would be doing wall-sits. If you are sitting up against a wall, you are exerting a force on that wall. What if the wall were not exerting that same force back at you? You’d fall over!
If you want even more information on Newton’s Third Law, check out this video from KhanAcademy:
Now that you know Newton’s Third Law of Motion tells us that for every action, there is an equal and opposite reaction, you will create a visual that demonstrates that statement. You are going to be making a paper car that’s powered purely by the air of a balloon!
Predict: How does this action/reaction pair relate to the demonstration you are about to create?
- Rubber band
- 3 Straws
- Creativity and a sense of fun!
Here’s what to do!
- Fold a standard piece paper in half, and then fold it in half again.
- When you open your piece of paper back up, you there should be fold lines that divide the paper into four sections.
- Cut down those lines so that you have four equal pieces of paper.
- Grab one of those pieces and two straws.
- Using tape, attach a straw to each of the short sides of the paper. Make sure the straws are centered so that the same amount of straw is hanging off the sheet of paper on either side. It should look something like this:
7. Grab a lifesaver and put it onto the straw so the straw is going through the center hole of the candy. The lifesavers are going to be your wheels.
8. In order to hold your wheels in place, wrap the tape around the straw on the outside of the lifesaver until it becomes thicker than the hole of the lifesaver so it won’t fall off the straw. Make sure your wheel can still spin!
9. Repeat step 7 and 8 to create your other three wheels.
10. Now you have the base of your car made. Use tape and your remaining paper to create walls for your car. Be creative!
11. Now, you need a source of energy to make your car move. Put the mouth of the balloon over the one end of your remaining straw. Wrap the rubber band around the mouth of the balloon about five times. It needs to be tight enough so air cannot escape, but not so tight that it crushes the straw. To make sure the rubber band is tight enough, blow air into the straw to blow up the balloon and then place your finger over the mouth of the straw to hold the air in. Listen closely... is air escaping? If so, wrap the rubber band tighter. If not, you’re good to go!
12. Now, you need to attach your balloon to the car. Tape the straw to the base of your car so that the balloon end is facing the front of your car and the straw end is hanging off the back. Picture your straw as an exhaust pipe. Once you secure the straw to your car, blow up the balloon by blowing into the straw and place your finger over the end of the straw to keep the air from escaping.
13. Set your balloon car on a level surface and remove your finger from the straw.
14. Zoom! Your balloon car is off! The air escaping the balloon is causing your car to move. For every action, there is an equal and opposite reaction.
15. Extension: Experiment with different car designs to see how design affects the speed of your car.