First Law of Motion: Objects in motion tend to stay in motion unless acted upon by an external force. Force is a push or a pull, like pulling a wagon or pushing a car. Gravity is a force that attracts things to one another. Gravity accelerates all things equally. Which means all things speed up the same amount as they fall.
Materials: ball
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Ok, sort of a silly experiment I admit. But here’s what we’re going for – there is an invisible force acting on you and the ball. As you will see in later lessons, things don’t change the way they are moving unless a force acts on them. When you jump, the force that we call gravity pulled you back to Earth. When you throw a ball, something invisible acted on the ball forcing it to slow down, turn around, and come back down. Without that force field, you and your ball would be heading out to space right now!
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Ever wonder how magicians work their magic? This experiment is worthy of the stage with a little bit of practice on your end.
Here’s how this activity is laid out: First, watch the video below. Next, try it on your own. Make sure to send us your photos of your inventions here!
It is very rare, especially on Earth, to have an object that is experiencing force from only one direction. A bicycle rider has the force of air friction pushing against him. He has to fight against the friction between the gears and the wheels. He has gravity pulling down on him. His muscles are pushing and pulling inside him and so on and so on.
Even as you sit there, you have at least two forces pushing and pulling on you. The force of gravity is pulling you to the center of the Earth. The chair is pushing up on you so you don’t go to the center of the Earth. So with all these forces pushing and pulling, how do you keep track of them all? That’s where net force comes in.
The net force is when you add up all of the forces on something and see what direction the overall force pushes in. The word “net”, in this case, is like net worth or net income. It’s a mathematical concept of what is left after everything that applies is added and subtracted. The next activity will make this clearer.
Here’s what you need:
