3 of 11

Notes for Teachers

This lesson can be done in 2-3 hours.
Students can make small groups of 3-4 members.
The focus of this lesson is to gather and analyze data.
Creative solution should be encouraged.

List of Materials

Plastic Cups

String

Notebook

Pencil

Digital Weighing Scale

4 of 11

Mathematical Practices

QR.MP.5 Use appropriate tools strategically.

QR.MP.6 Attend to precision.

AZ Standards for HS

Science & Engineering Practices

Planning & Carrying Out Investigations

Design and conduct an investigation individually and collaboratively, and in the design: decide on types, how much, and accuracy of data needed to produce reliable measurements and consider limitations on the precision of the data (e.g., number of trials, cost, risk, time), and refine the design accordingly.

Science Standard

HS+Phy.P3U1.3

Develop a mathematical model, using Newton’s laws, to predict the motion of an object or system in two dimensions (projectile and circular motion).

5 of 11

Objective(s):

Today we will describe how circular motion is caused by centripetal force.
Today we will explain the relationship between centripetal force and inertia.
Today we will interpret motion maps to describe circular motion.
Today we will use centripetal force concepts to solve problems.�

6 of 11

Agenda (180 minutes)

When does uniform circular motion happen?
Gather and analyze data.
Share or present.�

7 of 11

Intro/Driving Question/Opening

When does uniform circular motion happen?

Which of the following changes as the stone undergoes uniform circular motion? Why?

Speed?

Velocity?

Direction?

When you whirl a stone in a horizontal circle, what keeps the stone in circular motion?

8 of 11

Hands-on Activity Instructions

In a group of 3 physicists, students will investigate how the length of the string affects the speed and centripetal force on an object moving in a circular path at a constant speed.

Students will be using plastic cups, strings of three different lengths, digital weighing scale and water.

Use the document below for this activity.

Data Sheet

Students will be asked present their data to the class.

PROCEDURE

1. Get a plastic cup and a string.

2. Make a small hole on each side of the plastic cup.

3. Attach a 100cm length string on these holes.

4. Fill the plastic cup half-filled with water.

5. Measure the mass of the plastic cup half-filled with water. Record this on your data table.

6. Hold the end of the string that is attached to a plastic cup half-filled with water and whirl it horizontally above your head. Make sure that no water spills while doing this experiment.

7. When the plastic cup is constantly moving, take the time it covers to make 5 complete revolution or 5 circles.

8. Record the time and do this for 5 trials. Record this on your data table.

9. Do procedure 3 to 8 but this time, change the length of the string to 90 cm. Record your data.

10. Do procedure 3 to 8 but this time, change the length of the string to 70 cm. Record your data.

9 of 11

Assessment (Worksheet Assessment)�

APPLICATION

1. Was there a change in the performers computed tangential speed and centripetal force? What causes this change?

2. Why does water stay in a cup when you spin it? What keeps the water inside the disposable cup?

GRAPH

1. Are the dots close to each other or scattered?

2. What does it mean when the dots are closed to each other or when the dots are scattered?

10 of 11

Assessment (Oral Presentation)

Category	5	4	3-2	1
Scientific Knowledge	Explanations by all group members indicate a clear and accurate understanding of scientific principles underlying the construction and modifications.	Explanations by all group members indicate a relatively accurate understanding of scientific principles underlying the construction and modifications.	Explanations by most group members indicate relatively accurate understanding of scientific principles underlying the construction and modifications.	Explanations by several members of the group do not illustrate much understanding of scientific principles underlying the construction and modifications.
Organization of Presentation	Presentation were outlined in a step-by-step fashion that could be followed by anyone without additional explanations. No adult help was needed to accomplish this.	Presentation were outlined in a step-by-step fashion that could be followed by anyone without additional explanations. Some adult help was needed to accomplish this.	Presentation were outlined in a step-by-step fashion, but had 1 or 2 gaps that require explanation even after adult feedback had been given.	Presentation that were outlined were seriously incomplete or not sequential, even after adult feedback had been given.
Creativity of Presentation	Very original presentation of material; uses the unexpected to full advantage; capture audience’s attention	Some originality apparent; good variety and blending of materials	Little or no variation; material presented with little originality or interpretation	Repetitive with little or no variety; insufficient use of materials

11 of 11

Differentiation

Remediation

Extension/Enrichment

Students who are successful right away can now collaborate with other groups, compare their results and check for accuracy of the activity.

Students can explore the activity by changing some variables such as changing the mass of the plastic cup with water but keeping the length of the strings constant.

Number of trials for the hands-on activity can be reduced for students who are struggling in this lesson.

Another way to help students who are struggling is to pair them up with mathematically-inclined students. They can be useful in tutoring students especially in computation for tangential speed and centripetal force.