Hello I am Jared. Welcome to Fun Science Demos. Our friends at Educational
Innovations have some really cool science gadgets for sale and
today we are going to take a look at the reaction rocket, which helps us to take a
closer look at Newton's third law of motion. Newton's third law says that for
every action, there is an equal and opposite reaction, so let us see that at
work. When you open the packet up you will find a rubber ball with a straw attached
to it, and then two bigger straw rockets. They have little foam fins and then a
little plastic collar glued to the top of the rocket. So to take a closer look
at Newton's third law, let us just start with the ball and the straw. Let us bring
in our meter stick and I am going to hold the ball about 20 centimeters. now, when I
drop the ball there is going to be energy in the ball as it drops, and let us see
what happens once it hits the table.
So what happened there? When the ball hit
the table, well, the energy stored in that ball as it was falling is transferred to
the table, but some of that energy is also transferred back up into the ball,
propelling it upwards.
Now, you will notice that the ball did not bounce back to the full 20 centimeters
Well, why? Well, because some of that energy was transferred into the table so
there was not as much energy propelling it back upward. Now, something interesting
happens when we add our plastic straw rocket. we really could not see the energy
that is being transferred back into the ball propelling it upward but this
rocket is going to allow us to see that. So I slide the rocket over the straw and
I am just going to hold it up and I want you to watch the rocket.
You can see the rocket is propelled way higher because the mass of the straw is not anywhere near
what it is of this ball. So the energy in this ball propels this rocket upward.
Now, Educational Innovations is a great website and on that website they have a
paper that goes along with this reaction rocket, to see how this thing works and
one of their ideas is to try dropping the rocket, dropping the ball, at
different heights and see how high the rocket goes so we are going to try that
right now. Here is our meter stick. We are going to try dropping the rocket at 10
centimeters about 10 centimeters so let us see how high the rocket goes.
So the rocket came up somewhere around 40 centimeters. What happens if I try
dropping the ball at 20 centimeters? How high do you think the rockets going to
go? Let us try that again so it does not go straight out. our second drop - our rocket
went a little more than 80 centimeters. so what does that mean? well, the higher
up that I am dropping the ball in the rocket, that means the higher the Rockets
going to go. why ? well it is because the higher up I dropped the ball with the
rocket, the more energy it has. so the higher it goes. remember, a part of science
is measuring things so a neat activity would be to get yourself a meter stick,
to get yourself a piece of paper and a pencil, and to try dropping the rocket
from different heights and recording how high that goes. I wonder what happens if
I would drop the ball from really high up. try it and find out. I
wonder what would happen if I try dropping the
ball at fifty centimeters? well I can try it and find out. and that rocket about
hit the ceiling. you can see it was way higher than my meter stick. so, we could
have a lot of fun measuring things with our rocket drop. now, I want to take a
closer look at that energy that is being transferred, so keep in mind when we drop
the ball without the rocket it comes up a pretty decent amount. now I want you to
watch how high that ball bounces up once I have the rocket on. do not watch the
rocket, watch the ball's height. you could see the ball barely came off the table.
that is because all the energy in that ball was being transferred to this
rocket, and that is what made the rocket go so high. get your own reaction rocket
kit from Educational Innovations and try this on your own. It is a lot of fun and
do some measuring because measuring is a key part of science. We put a link to
Educational innovations website so you can buy your own reaction rocket! If you
want to learn more about forces in motion or just science, check out our
channel, FunScienceDemos. Science is so cool! Thanks for watching.