Young Engineers: Class 3 Catapult - Sturdy and Fun DIY Engineering Activity for Kids

Summary

In this video, Lance demonstrates how to construct a class 3 catapult using craft sticks, cubes, and rubber bands. He explains the lever principle behind it, detailing each step from assembling the base to attaching the arm and rubber bands. Lance also shares tips for optimizing the catapult's performance by experimenting with different projectiles and adjusting the arm's length, emphasizing the impact of projectile characteristics and the arm's potential speed due to its distance from the fulcrum.

Takeaways

• 🔨 The class 3 catapult is a demonstration of a class 3 lever, utilizing a fulcrum, load, and effort.
• ✂️ Start by cutting or breaking three craft sticks in half using pliers or wire cutters.
• 🔗 Connect two regular craft sticks with one half stick piece and glue additional sticks to form the base structure.
• 🔩 Build triangular supports on the sides of the base and add half stick pieces to the top of the triangles.
• 🏗️ Create a catapult arm by gluing two craft sticks together with a third one in the middle.
• 🔄 Attach the arm to the base using a thin dowel as a hinge, ensuring the arm can move freely.
• 🔁 Loop rubber bands around the catapult arm to provide the necessary tension for launching.
• 🎯 Attach a plastic cup to the end of the catapult arm using both glue and tape for stability.
• 🚀 Experiment with different projectiles to find the optimal density, weight, shape, and size for distance.
• ⚖️ Adjust the length of the catapult arm to increase speed and performance, considering the trade-off with inertia.

Q & A

What is the main concept demonstrated in the video?

The video demonstrates how a class 3 lever works using a catapult as an example.

What materials are needed to build the catapult as described in the script?

The materials needed include craft sticks, hot glue, a pair of pliers or wire cutters, a thin dowel, rubber bands, and a plastic cup.

How many craft sticks are cut in half at the beginning of the project?

Three craft sticks are cut in half at the beginning of the project.

What is the purpose of the gap between the two cubes with holes on the base of the catapult?

The gap between the two cubes with holes is left open to accommodate the dowel that will act as the hinge for the catapult arm.

How is the catapult arm constructed?

The catapult arm is constructed by creating a beam that's two craft sticks long, connected in the middle with a third craft stick, and repeating the process once more.

What role does the thin dowel play in the catapult's mechanism?

The thin dowel acts as a hinge, allowing the catapult arm to move up and down.

How are the rubber bands attached to the catapult arm?

The rubber bands are looped around the catapult arm, pulled under the stop bar at the top, stretched out, and looped back over the arm again.

What is recommended for the catapult's projectile, and why?

Foam cubes are recommended as projectiles because they are dense enough to go far but not likely to break anything, making them suitable for indoor use.

What factors can affect the performance of the catapult when launching projectiles?

The density, weight, shape, and size of the projectile can significantly affect the catapult's performance.

How can the length of the catapult arm impact the catapult's effectiveness?

A longer catapult arm can allow for faster movement due to greater distance from the fulcrum, but it may also require more energy to move and might need additional or different rubber bands for optimal performance.

What are two things viewers can experiment with to improve their catapult's performance?

Viewers can experiment with different projectiles and the length of the catapult arm to improve performance.

Outlines

00:00

🔨 Building a Class 3 Catapult Model

In this video, Lance demonstrates how to construct a class 3 catapult using craft sticks and other simple materials. The process begins by cutting craft sticks, connecting them with hot glue to form the base, and ensuring the alignment of holes for the pivotal movement. Lance then constructs the catapult arm, which is a beam made of craft sticks, and attaches it to the base using a thin dowel as a hinge. Rubber bands are used to provide the necessary tension and power for launching projectiles. Lance suggests experimenting with different projectiles and adjusting the length of the catapult arm to optimize performance. The video concludes with a demonstration of the completed catapult launching foam cubes.

Keywords

💡Catapult

A catapult is a mechanical device used to launch projectiles. In the video, the focus is on building a simple catapult using craft sticks, cubes, and rubber bands to demonstrate the principles of a lever. The catapult launches foam cubes, showcasing how the energy stored in the rubber bands propels the projectile.

💡Class 3 Lever

A Class 3 lever is a type of simple machine where the fulcrum is on one end, the load is on the other end, and the effort is applied somewhere in between. The video explains how the catapult works as a Class 3 lever, with the fulcrum at the base, the effort applied by pulling the arm, and the load being the projectile.

💡Fulcrum

The fulcrum is the pivot point of a lever. In the video, the fulcrum is located where the catapult arm is attached to the base, allowing the arm to pivot up and down when launching the projectile.

💡Effort

Effort refers to the force applied to a lever to move a load. In the context of the catapult, the effort is applied when the user pulls back the catapult arm, stretching the rubber band, which stores energy to launch the projectile.

💡Load

In the video, the load is the projectile that the catapult is designed to launch. The foam cubes used in the video are examples of the load, and the user is encouraged to experiment with different types of projectiles to see how they affect the distance and performance of the catapult.

💡Rubber Band

The rubber band in the catapult acts as a source of potential energy. When the catapult arm is pulled back, the rubber band stretches, storing energy. Upon release, this energy is transferred to the arm, causing it to snap forward and launch the projectile.

💡Projectile

A projectile is an object that is launched into motion by a force. In the video, foam cubes are used as projectiles, but the user is encouraged to experiment with different objects to understand how size, shape, weight, and density affect the catapult's performance.

💡Dowel

A dowel is a thin, cylindrical rod. In the video, the dowel is used as a hinge for the catapult arm, allowing it to move up and down. The dowel is inserted through the cube holes to hold the arm in place while still enabling movement.

💡Inertia

Inertia is the tendency of an object to resist changes in its motion. In the video, the presenter explains how a longer catapult arm has more inertia, meaning it requires more energy to move. This concept is important when experimenting with different arm lengths to optimize the catapult's performance.

💡Energy Transfer

Energy transfer refers to the movement of energy from one object or system to another. In the context of the catapult, energy is stored in the rubber band when it is stretched and is then transferred to the catapult arm when released, propelling the projectile forward.

Highlights

Introduction to the Class 3 catapult as an example of a Class 3 lever

Instructions to cut or break three craft sticks in half

Connecting two regular craft sticks with hot glue

Gluing two regular cubes at the corners above the half stick piece

Creating a base with cubes and ensuring the holes line up

Building the triangular supports on the sides of the base

Gluing half stick pieces onto the sides of the cubes

Building the catapult arm with two craft sticks connected in the middle

Gluing a regular cube and a cube with holes onto the catapult arm

Installing the arm onto the catapult using a thin dowel

Securing the arm's movement with the dowel as a hinge

Adding rubber bands to the catapult arm for launching

Attaching a plastic cup to the catapult with both glue and tape

Launching the catapult with a foam cube as a projectile

Experimenting with different projectiles for distance and performance

Exploring the impact of catapult arm length on performance

Considering the trade-off between arm length and required energy

Conclusion and invitation to watch more videos

Transcripts

[Music]

hey my name is lance

the class 3 catapult is a great example

of how a class 3 lever works where

there's a fulcrum on one end

the load on the other and the effort is

somewhere in the middle

so let's get started first cut or break

three craft sticks in half you can do

this with a pair of pliers

or by cutting with a pair of wire

cutters first connect two regular craft

sticks together using hot glue

and one of the half stick pieces flip it

over

then glue two regular cubes at the

corners that are above

the half stick piece and then glue two

cubes with holes onto the other end

making sure that the holes line up then

glue more sticks all along the sides of

the base

and on the top

make sure not to glue any sticks in this

gap between the two cubes with holes

next build the triangular supports on

the sides

of the base

and glue two regular cubes to the top of

each of those triangles

then glue the remaining half stick

pieces onto all four sides of these

cubes

[Music]

okay now we need to build the catapult

arm create a beam that's two craft

sticks long and connected in the middle

with a third craft stick repeat one more

time

[Music]

then on one of the beams on the side

that has the two craft sticks lined up

with each other

glue on a regular cube in the center and

on one of the ends

[Music]

then glue a cube with holes onto the

other end making sure that the holes are

pointing off to the sides of the beam

like this then glue the other beam on

top of all three of those cubes

okay to install the arm onto the rest of

the catapult we first need to get

a thin dowel and cut or break it to size

so

it's the same width as the base

now put the catapult arm through the

middle of the base with the cube

on this side put the dowel piece through

the cube with holes

then put one end of the dowel through

one of the cubes with holes on the base

and carefully pry the base apart so it's

wide enough

for the dowel to fit into both of those

cubes

[Music]

the arm should be able to move up and

down on this hinge

okay next we're going to add the rubber

bands loop it around

the catapult arm then pull it under

this stop bar at the top stretch it out

and loop it back over the catapult arm

again

now when the arm is pulled back the

rubber band gets stretched out

and when released you'll snap the arm

forward the last step

is to both glue and tape a plastic cup

on

if you use just glue or just tape then

the cup will break off

when the catapult is launched to launch

the catapult load your projectile of

choice

i like using these foam cubes because

they're dense enough to go far but

they're not going to break anything

then use one hand to hold down the base

while the other hand

grabs the cube at the very end of the

catapult arm pull all the way back

and then just let go okay so that's how

to build it

now there are two things that you can

experiment with to make your catapult

work even better

the first thing are the projectiles i

use these foam cubes because i can shoot

them indoors without breaking things but

they are not the best

thing to fire from the catapult if

you're trying to go for distance

try shooting different things out of the

catapult to see what can go the farthest

the density weight shape and size of the

projectile makes a huge difference in

how well the catapult can perform

and the other thing that you can tinker

with is the length of the catapult arm

so right now when i pull the capital arm

back and then let go

the energy from the rubber bands is

accelerating this cup up

and forward but if the catapult arm was

longer

then it could go faster because when

things are farther away from the axis of

rotation

or in this case the fulcrum they will

move at a faster speed

however a longer catapult arm is going

to be heavier and it's going to have

more inertia or it's going to take

more energy to get it moving so you may

need to add more rubber bands or

different kinds of rubber bands

to best take advantage of that added

length okay that's all for this video

thanks

so much for watching and i'll see you

next time

um