Vocabulary: Newton Force Joule Work Mechanical advantage   Materials: journal to record data scissors string meterstick book or objects to test spring scale

Preparation:

1. Cut a piece of string 1m long.
2. Each student select two or more objects to test. You will suspend objects individually from a spring scale, i.e., book, shoe, etc.

Procedure:

1. Determine what is force (push or pull on an object), newton (the international unit of force), work (when an object moves as a result of a force acting upon it), joule (a unit of work), mechanical advantage (the number of times a machine multiplies the effort/force- MA=distance divided by height).
2. Record that one joule of work is performed when a force of one newton moves an object a distance of one meter, i.e., Work=Force x distance.
3. Measure the force required to lift various objects a premeasured distance, then calculate the amount of work that was done.
4. Distribute a spring scale, string and a meterstick to student groups. Demonstrate how to use a spring scale, calibrating if needed if it fails to point to 0 newtons with no load attached.
5. Lift a variety of objects with the spring scale, note the newtons of force required to lift each object, measure the distance that each object is lifted, and then calculate the amount of work accomplished.
6. Create a chart by columns listing the ‘Object’, ‘Force’ (newtons), ‘Distance’ (meters), and ‘Work’ (joules) at the top of the columns.
7. Weigh each object from the spring scale, and then record each weight in the ‘Force’ column.
8. As you raise each object, record the height an object is lifted in the ‘Distance’ column.
9. Find the amount of work done on each object by multiplying the weight of an object by the distance it was lifted. Record the results in the ‘Work’ column.

Analyze and Conclude (record your observations in student journals):

• Describe the relationship between the weight of an object and the work that is done to lift it.
• Describe the relationship between the height that an object is lifted and the work that is done to lift it.
• If an object weighing (3) newtons is lifted (2) meters high, then another object weighing (6) newtons is lifted (1) meter high, how is the amount of work done compared from one object to the other? How do you know?