Return to Biology IndexMeasuring Work

Cynthia Clemons John Palmer

5051 N. Kenneth Ave.

Chicago IL 60630

(312) 534-3704Objectives:

Students will explain what work is, measure work done in moving an object, and

tell how energy is related to work in both machines and the human body.Materials Needed:

meter stick, bathroom scale, paper, pencil, and a flight of stairsStrategy:

Part-A: How Much Work Can Your Body Do?1. Students will walk up a flight of stairs, counting the number of stairs in the flight. 2. Students should measure (in centimeters) the height of one stair and multiply that number by the number of stairs in the flight. This will give them the distance. 3. Students weigh themselves using an ordinary bathroom scale and calculate their weight in N (Newtons). 1 lb equals 4.5 N. This will give them the force. 4. Finally, students will calculate how much work is done when they walk up a flight of stairs. Work is measured in N-meters. The formula for measuring work is, W = F x D.Performance Assessment:

-Student correctly uses the meter stick to measure the height of one stair.

-Student correctly weighs himself using an ordinary bathroom scale.

-Student correctly calculates his weight in newtons.

-Student correctly calculates the distance in meters.

-Student correctly calculates the amount of work done in walking up a flight of

stairs.

Part-B: Can Simple Machines Help Us Do Work?Materials Needed:

construction paper (13 cm x 13 cm), straight pin, ruler, unsharpened pencil

(with an eraser), 45 cm length of string, one-quart size milk carton, scissors,

paper clip, a heavy objectStrategy:

1. Students build a model windmill using the 13 cm x 13 cm piece of

construction paper, the straight pin, and the unsharpened pencil.

2. Students should cut the top off the milk carton. Then cut 2 deep U-shaped

groves in opposite sides of the milk carton. Put a heavy object into the

carton to weigh it down.

3. Tie a paper clip to one end of a piece of string. Tape the other end of the

string to the writing end of the pencil.

4. Set the windmill into the groves of the milk carton at the edge of a table so

that the paper clip on the string hangs freely.

5. Students predict what will happen when air is blown across the top of the

windmill so that the blades catch the moving air.

6. Students should (by mouth), lightly blow across the top of the windmill so

that the blades catch the moving air.Performance Assessment:

-Student is able to make a reasonable prediction concerning the performance of

the windmill blades.

-Students can reasonably describe what happened when air was blown on the blades

of the windmill.

-Student is able to conclude that moving air on the wheel and axle of the wind-

mill allows the windmill to act as a simple machine.

Part-C: Our Body the Machine:Materials Needed:

Pictures of foods, glue, scissors, construction paper, play food to represent

the four food groups, chart of the four food groups, chart showing the

recommended daily nutritional requirements, and a chart that shows the nutrients

found in some common foods. The chart should also include examples of food

sources and the body's need for each nutrient.Strategy:

1. Students will run in place, and perform a set of jumping jacks.

2. Ask students what allows them to be able to perform these simple exercises?

3. Tell students that the energy needed to perform these simple exercises, comes

from the varied foods they eat.

4. Students use a nutrition chart to examine some common foods, their

nutritional value, and how the food supplies the body with energy.

5. Students give examples of "junk foods" and "healthy foods."

6. Students identify the four food groups and classify play food into the four

groups.

7. Students describe a balanced diet.

8. Students create a balanced lunch using some common lunch items.

9. Students use pictures of food items to create a collage that represents a

balanced breakfast, lunch, and dinner.Performance Assessment:

-Student correctly classifies foods into the four food groups.

-Student creates a collage of food choices that reflect a balanced breakfast,

lunch, and dinner.

(See the activity sheet on the next page.)

Activity Sheet: Part-A

How Much Work Can Your Body Do?Materials: meter stick, bathroom scale, pencil, paper, and a flight of stairsProcedure:

A. Weigh yourself in lbs. Calculate your weight in Newtons (1 lb equals 4.5

Newtons).

B. Walk up a flight of stairs. How many stairs are in the flight?

C. Measure the height of one stair.

D. Calculate the distance (The bottom of the flight to the top).

E. Calculate how much work you do in walking up the flight of stairs.

Data Sheet

1. My weight is _____ lbs

2. The force I will use is my weight in Newtons. The force is _____

WORK SPACE _____lbs x 4.5 Newtons = _____

3. The height of one stair is _____ cm

4. The number of stairs in the flight is _____

5. The distance I will walk is _____ meters

WORK SPACE height of one stair _____ x _____ the number of stairs in the

flight

6. Walk up the entire flight of stairs

7. How much work did you do when you walked up the flight of stairs?

_____ Newtons x _____ meters (distance) = _____ Newton-m of work

8. I can infer that a person with a __________ weight will do less work than a

person with a __________ weight when walking up a flight of stairs