Marshmallow Catapult
Aim: To construct marshmallow catapults and record its height and distance.
Equipment: Marshmallows (1 Packet), Rubber Band, Plastic Spoon, Wooden Skewers ( 7 ) & Tape.
Method:
1. Place three marshmallows in a triangle, them connect them with skewers.
2. Take a skewer and stick it onto the top of the marshmallow.
3. Bring the tops of all three skewers and stick them together with one marshmallow.
4. Take a spoon to another skewer.
5. Stick this skewer into one of the marshmallows below the skewer already placed.
6. Take the rubber band and wind around spoon and then loop end of the rubber band around the marshmallow and bringing it underneath the marshmallow {should not be on marshmallow}.
Results:
Unfortunately, we were not able to measure the height of the flying marshmallows but did get the distance.
Discussion:
Before we even applied any force or energy on to our catapult, there were already forces acting on the object. This was support and weight force. These forces were keeping the catapult at an upright position, the forces were balanced. This meant that the object was motionless. As we pulled down the catapult kinetic energy was changed into elastic potential energy. When the spoon was pulled down it also gained elastic potential and as we released it converted the energy into motion. As it flew through the air it gained gravitational potential energy. The marshmallow gained as much gravitational potential energy until it stopped at a height which it could no longer go higher and started falling down again, which then was converted into kinetic energy as it fell back down again.
Definitions:
Support Force: is a force that balances the weight of an object.
Weight Force: Weight force is the force of gravity on an object.
Kinetic Energy: When an object is in motion kinetic energy is created.
Elastic Potential Energy: An elastic which can store energy and convert it into motion.
Gravitational Potential Energy: Energy an object has when off the ground.
Structures:
We found out that different catapults gave us different results. We had three catapults:
Catapult 1: Was the spoon catapult.
Catapult 2: Was the catapult with the purple bottle cap.
Catapult 3: Was the catapult with the small metal cap.
These are some results involving distances from our experiment:
Catapult 1
|
Catapult 2
|
Catapult 3
| |||||
Small
|
Big
|
Small
|
Big
|
Small
|
Big
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0.5
|
0.8
|
4.1
|
3
|
2.2
|
0.3
| ||
2
|
0.9
|
4.2
|
5
|
2.5
|
1
| ||
2.5
|
0.9
|
4.4
|
5.7
|
3
|
1.8
| ||
3.5
|
1.1
|
5.8
|
5.7
|
3
|
2
| ||
3.8
|
1.4
|
6.3
|
6.9
|
3.1
|
2.3
| ||
4.6
|
6.5
|
6
|
3.4
| ||||
4.9
|
8.3
| ||||||
5.8
|
5.8
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5.8
|
4
| ||||||
6.3
| |||||||
6.4
|
As we can see catapult two has the longest small marshmallow throw (8.3m). And, catapult two has the longest big marshmallow throw (6.9m). This is becasue of its structure, catapult two has a bigger structure and more elasticity. This means it's able to bend back further building up more elastic potential to fling further. The more it bends back the further it goes. We can also see that catapult three is not able to fling marshmallows further than 4m because of its size. Catapult three is 2x smaller than catapult two which means it's not able to bend back as much and gain as much elastic potential energy. When bending catapult three we are bending the wood, which is not ideal as it is stiffer. Catapult one is the design we made, it has a spoon as the material we bend back, this means it is bendier. It is quite small than means it does not bend all the way back. In conclusion, without a doubt, the best catapult would be catapult two.
Calculating Gravitational Potential Energy:
