Embedded Files
WORKING WITH STRUCTURES 3RD OF ESO
BALANCING BIRD TOY
The balancing bird is a toy that has its center of gravity located at the tip of the beak. The center of gravity (also called the center of mass) is a special point on an object. It's the point at which the mass of the body is perfectly balanced.
In this particular case, it might seem strange that the bird is perfectly balanced at the beak location. But this is because the bird is designed this way. The wings are extended in front of the beak far enough, and made heavy enough, to balance the weight of the bird behind the beak.
As an activity of the Structures unit, 3rd of ESO students made a balancing bird toy at class. With this activity students had a more deep comprehension of the concept of center of gravity.
You can do it yourself at home too. The material needed is the following:
cardstock
scissors
toothpick
pennies
tape
crayons, markers, colored pencils (optional)
Follow the instructions:
Download the bird template. Print it on cardstock, or print it on regular paper and trace the shape onto cardstock. Cut the bird out along the outline. You can use a file folder or cardboard from a cereal box, just make sure the bird cutout doesn’t have any folds or creases in it. If you’d like, you can color your bird.
Try balancing the bird by putting the beak on your finger. Does it stay?
Fold the straw in half and tape it to the underside of the bird so the center of the straw is just behind the head and the bent sides extend under the wings. Tape one penny near the tips of the wings on the underside of the bird. Try to put them the same distances from the edges on both sides. Flip the bird over. Place the tip of the bird’s beak on your finger and it should balance.
WHAT’S HAPPENING? For an object to balance, it needs to be supported directly underneath its center of gravity. The center of gravity is the point where all weight is evenly dispersed and all sides are balanced. Without the pennies, the bird can’t be balanced on its beak because the center of gravity is near the middle of the bird. When the pennies are put on the wings, the center of gravity is now located at the tip of the beak and it can be balanced on a fingertip.
Película mágica.mp4CENTER OF GRAVITY CHALLENGES
Did you ever come across a challenge that looked almost too easy to try but turned out to be surprisingly difficult, if not impossible? These activities have challenged our 3rd ESO students in a fun way. Something as simple as picking up a coin can be way harder than it looks.
Watch the video and you will find some fun challenges involving the center of mass of your own body. When you're standing straight, your centre of gravity is somewhere around your belly button. When you change your body's shape, you shift the centre of gravity a bit.
First challenge: The chair lift.
WHAT HAPPENED? Results of this challenge may vary by gender. Interestingly enough, many girls can successfully complete this challenge, while most boys cannot. Why? Again, it’s all about the center of mass. The center of mass for most girls is lower to the hips, while the center of mass in boys is much higher. Therefore, for most girls, the center of mass while bent over the chair is above their feet, while the center of mass for most boys is above the chair.
Second challenge: The thumb press
WHAT HAPPENED? The reason it’s so hard to stand up is because your center of mass is located over the seat of the chair rather than over your feet, which are in front of you.
Third challenge: The coin grab
WHAT HAPPENED? The reason this challenge is so difficult is because of our anatomy—specifically, our bottoms. As you bend over to pick up the coin, your rear end naturally extends backward to help keep your body balanced. Since it’s pressed against the wall, your bottom has no where to extend. This causes the center of mass to shift forward, resulting in falling forward—at least for most people.
Spaguetti Towers Second edition.movSPAGUETTI TOWERS SECOND EDITION
Last year, 3rd ESO students made a contest that consists in building spaghetti towers using this material and marshmallows also as a final activity of the Structures unit.
This year’s students did also the same activity. They gathered in groups of 4 or 5 with the same amount of spaghetti and marshmallows. The objective of the activity was to build a tower as high as possible using the given materials in 40 minutes. The aim of the task was to experience that the triangle is the most stable shape when a frame structure is built. When forces are applied to a four-sided structure with corner pivots (in this particular case, marshmallows) it can be easily forced out of shape. This structure is non-rigid. By adding a diagonal member, connected corners are held at a fixed distance. They can’t be spread apart or moved closer together. Despite pivots for corners, the structure cannot be forced out of shape, and is rigid. Notice that the additional member has formed two triangles in the structure. This is called triangulation.
The activity was performed in three different group classes. These are the winners:
3rd A
3rd A
74 cm H
3rd B
3rd B
95 cm H
3rd C
3rd C
85 cm H
Page updated
Report abuse