Summary Experiment with things that balance, starting simple to understand how it works, and make a mobile Science content Physics: Motion and Forces, Newton’s Laws, Gravity (K, 2, 6) Activities in this lesson Balance point on a stick or ruler Mobile Balancing sculpture Procedure Start with finding the balance point of a long stick, to understand how the balance point moves as the mass is redistributed. Conclude: the balance point moves towards the side with the greater mass. Optional: include quantitative measurement of the balance point on a ruler, and graph it. What about where the mass is placed? We’ll use a lighter pivot, and the numbers allow us to do some measuring which we can put on a graph. Conclude: The further out the mass is, the further over the balance point moves. The mass has more of an effect when it is further away. Make a mobile, using the principals learned above to quickly assess where the balance point of each stick is. Experiment with the centre of mass with a balancing sculpture. Discuss that without the weights the grape/toothpick is unstable and falls because the mass is above the balance point. It moves til the mass (or the average of the distributed mass; centre of mass/gravity) is low as possible. Adding weight below lowers the centre of mass. Predict then try apple, banana. The clay and skewer sculpture can be presented as a challenge "how can you balance a toothpick on your finger?" after showing the grape/fork trick. If time: Balancing your body challenges Grades taught Gr 4 Gr 5 Teaching Site ingridscience afterschool
