Force, Displacement and Acceleration Lab Lesson Plan

Overview:
In this activity student will investigate how velocity and acceleration vary when pulling force remains constant, but the opposing force changes. Depending on time, possible extensions could include converting force from pounds to newtons, and determining the force vectors involved.
Content Standards:
Physical Science
Students will develop an understanding of the characteristics and interrelationships of matter and energy in the physical world.

Benchmarks:
PS-H-A1
manipulating and analyzing quantitative data using the SI system;
PS-H-E2
understanding the relationship of displacement, time, rate of motion, and rate of change of motion; representing rate and changes of motion mathematically and graphically;
PS-H-E3
understanding effects of forces on changes in motion as explained by Newtonian mechanics;

Grade-Level Expectations (GLEs):
Motions and Forces
Grade 9-12
9. Describe and measure motion in terms of position, displacement time, and the derived quantities of velocity and acceleration

(PS-H-E2)

10. Determine constant velocity and uniform acceleration mathematically and graphically

(PS-H-E2)

14. Add and resolve vectors graphically and mathematically to determine resultant/equilibrant of concurrent force vectors

(PS-H-E3)

33. Calculate velocity and acceleration using equations

(PS-H-E2)

34. Demonstrate Newton's three laws of motion (e.g., inertia, net force using F = ma, equal and opposite forces)

(PS-H-E3)

Measurement and Symbolic Representation
1. Convert metric system units involving length, mass, volume, and time using dimensional analysis (i.e., factor-label method)

(PS-H-A1)

2. Gather and organize data in charts, tables, and graphs

(PS-H-A1)

Interdisciplinary Connections:
Mathematics : Measurement
In problem-solving investigations, students demonstrate an understanding of the concepts, processes, and real-life applications of measurement.
Mathematics : Data analysis, Probability, and Discrete Math
In problem-solving investigations, students discover trends, formulate conjectures regarding cause-and-effect relationships, and demonstrate critical thinking skills in order to make informed decisions.

Educational Technology Standards:
Refine knowledge and enhance skills in keyboarding, word processing, desktop publishing, spreadsheets, databases, multimedia, and telecommunications in preparing and presenting classroom projects.
Use appropriate technology to locate, retrieve, organize, analyze, evaluate, and communicate information for problem solving and decision making.

Objectives:
1. The students will demonstrate an understanding of the effect of changing the resistance force on acceleration by showing their results in data tables and graph form.
Lesson Materials and Resources:
See the reproducible materials list.
Technology Tools and Materials:

Hardware:
Furniture dolly or garden cart
Spring balance(measures in Newtons)
Stopwatches( at least 3)
Meterstick
Masking tape
Computer and LCD projector or TV monitor
Bathroom scale

Software:
Graphical Analysis

Websites:
•Newton's three laws, Newton's first law, Newton's second law, Newton's third law, Force and vectors.

Background Information:
The students should be familiar with the feeling of being "pushed" into the seat as a car goes from a stop to a certain speed. We know that this feeling is due to the acceleration of the car and our body's own inertia. Students may understand that pushing down on the gas makes a car accelerate, but in this activity students will investigate how keeping certain forces constant and varrying other forces effects acceleration.
The Unitedstreaming video clips could be used as a preview to this activity.

Lesson Procedures:

1. Prior to performing this activity the teacher will need to mark out a course on a level, smooth, and straight floor. With tape, mark across the course at distances of 0 m, 5 m, 10 m, and 15 m. You shoul make sure that you course is wide enough for the cart to be pulled through, and that there is enough room on the sides for the "observers".
2. Designate one student to be the "puller". This student should be strong enough and coordinated enough to pull the cart with a constant or near constant force. (This means that they will also need to be quick enough to stay ahead of the cart!)
3. Designate three students of different sizes to ride in the cart and provide the resistance force. Have the students weigh on the bathroom scales, post these weights in pounds and have the other students convert this to kilograms and then to Newtons.
4. At each of the pre-measured distances, have groups of students with stopwatches and "recorders" with paper to record the times at each distance after each trial.
5. Have the "puller" attach a spring scale to the cart to be used and put one of the "riders" in the cart. The "puller must understand that their pulling force must remain constant. ( you may have to do some experimenting before the activity to determine the force used. I have had good results with 10 Newtons, but the force you use will depend on the mass of the cart, the masses of the "riders", and how well the wheels of the cart are lubricated). The "puller" will be tempted to increase the pulling force to get the cart moving. Advise against this since it will invalidate the results.
6. Have another student hold the cart back as the "puller" applies the predetermined force on the spring scale. When that force is reached, the cart should be released. At this point a signal must be given to the "timers" to start their stopwatches. The "puller" must now move backward to maintain constant force.
7. As the cart reaches each line, the "timers" stop their stopwatches. At the end of each run they will tell the "recorders" the times.
8. You should have some large students at the end of the course to help stop the cart.
9. Do three different runs with each student, then change the force applied and repeat the entire activity.
10. The students now have instantaneous velocities, and accelerations that can be averaged and put into graphs.
11. As a physics extension, the students can draw free-body diagrams showing the resultant vectors for each of the three opposing forces.

Assessment Procedures:
1.The students will be assessed on the accuracy of their data tables and will answer constructed response questions that deal with the activity.
2. The students will be assessed on the accuracy of their graphs of the data gathered.
3. Scientific drawings rubric
Accommodations/Modifications:
This is a group activity for the entire class. As such, there should be something that every student can do regardless of ability. Often they will be working close to other students that are doing the same task and I encourage the students to compare results. It will be up to the individual teacher to determine where each student will be best suited.