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A push or pull is a force. A force changes the way an object moves. You need different amounts of force to move different objects. The heavier the object, the more force you need to move it. |
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What happens to a ball if you throw it into the air? Gravity will pull the ball down. The earth's gravity is a force that pulls objects toward the center of the earth. The more mass an object has, the more gravity pulls on it. |
| Imagine rolling a ball across a floor. Think about how the ball would stop moving. Friction is a force that makes moving objects slow down or stop. The friction between the ball and the floor would make the ball stop moving. Rub your hands together. Notice how your hands feel warm when they rub together. Friction causes heat. Different surfaces cause more friction. Practice finding what surfaces require more friction. |
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Work is done whenever a force makes an object move. You do work when you move a pencil across the desk. The amount of work you do depends on how much force you use and how far the object moves. |
Review: Review what you learned about force, gravity and friction at the following site: |
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Your Assignment Design an Experiment using the scientific method that will answer the question: Which of the following has the greatest affect on an objects ability to stop: speed, the surface or weight?
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