suggest a project on magnetism or simple machines.
Answers
Answer:
suggest a project on magnetism or simple machines.
Explanation:
1. Introduce the concept that simple machines make work easier.
Tell the class the definition of work used in science may differ from what most people think of as work. Work can be defined as force times distance (Work = Force x Distance). Ask a student to move a book from one desk to another. Ask: Is this work by the scientific definition? (Yes, this is work.) You are applying force for a certain distance. Ask: Is doing homework work by this definition? (No, homework is not work.) Pushing a book across a desk is work because you are applying a force (a push) on a book for a certain distance (the length of the desk). You are not pushing homework anywhere.
Imagine that you want the same amount of work to get done using less force. In this example, this means you still want the book to move from one side of the desk to the other, but you don’t want to push as hard. If you use half as much force to push the book, then you will have to push the book twice as far to do the same amount of work. Or, you could use a simple machine to make up the difference in the force you are applying. Explain that people often use simple machines to make work easier.
Introduce the class to the names of various simple machines and show them a picture of each from the Simple Machines photo gallery: levers, the wheel and axle, pulleys, screws, and inclined planes. Tell the class simple machines make work easier by increasing mechanical advantage. Tell students that an example of mechanical advantage is using the claw of a hammer to remove a nail. A small force applied to the handle of the hammer produces a greater force at the claw end of the hammer, allowing for the removal of stubborn nails.
Explain that complicated machines, such as robots and cars, are made up of combinations of simple machines and other parts. Robots are complex machines that contain many simple machines. Some examples of simple machines that are used in robot construction are wheels and axles for mobility, allowing robots to move from place to place, and robot arms, which are levers, enable them to manipulate objects.
Explain that students are going to try simple experiments with simple machines, and then use those simple machines to solve challenges.
2. Demonstrate how levers work.
Construct a lever by taping a marker parallel to the edge of the table. Tear off a piece of masking tape, loop it, and attach it to the end of the ruler. Place the ruler on the marker at the center point, like a seesaw, and then press a tennis ball firmly to the tape. Invite a student volunteer to demonstrate the lever; first, have the student gently lift the ball by applying force to the end of the lever (ruler) opposite the ball. Second, instruct the student to reposition the lever (ruler) so the ball is as close to the fulcrum (marker) as possible. Have the student press the lever again to lift the ball. Lastly, reposition the lever (ruler) so the ball is as far away from the fulcrum (marker) as possible while still leaving a portion of the lever (ruler) to be pressed down. Have the student press the lever to lift the ball again. A photo of each lever situation is available in the Simple Machines Demonstrations photo gallery.
Discuss what the class saw and what the volunteer observed. Ask: Which lever configuration made the ball easiest to lift? Which lever configuration made it the most difficult to lift the ball? Which lever configuration moved the ball the farthest from its starting position? How does the lever provide a mechanical advantage when moving the ball?