# Analyzing Forces and Motion Graphs by Riding an Elevator

#### Summary

Students will make predictions of what a force vs time and acceleration vs time graph will look like for a ride in an elevator going down and up. Students will collect data remotely using a Force Plate and accelerometer and then download the data to the computer for further analysis. They will be asked to draw Free Body Diagrams at different points in the motion, calculate forces and compare this to the data retrieved from their computer graphs. A worksheet is attached that guides them through the inquiry process.

## Learning Goals

This activity is designed for students to

1. Predict force vs time graphs for motion in an elevator ride.

2. Analyze data from the elevator ride to calculate Net Force and accelerations for various parts of the ride.

3. Connect this data analysis to a Free Body Diagram for various parts of the ride.

Concepts:

1. Students will understand how to draw free body diagrams for various situations

2. Students will understand the difference between net and normal forces and what the force plate measures during the experiment.

3. How Force graphs relate to actual motion.

Vocabulary:

1. Net Force

2. Normal Force

3. Free Body Diagram

4. Acceleration

1. Predict force vs time graphs for motion in an elevator ride.

2. Analyze data from the elevator ride to calculate Net Force and accelerations for various parts of the ride.

3. Connect this data analysis to a Free Body Diagram for various parts of the ride.

Concepts:

1. Students will understand how to draw free body diagrams for various situations

2. Students will understand the difference between net and normal forces and what the force plate measures during the experiment.

3. How Force graphs relate to actual motion.

Vocabulary:

1. Net Force

2. Normal Force

3. Free Body Diagram

4. Acceleration

## Context for Use

This lab activity is appropriate for a high school level physics class or AP Course. It should take 45-55 minutes of class time. This lab requires the use of data collection probes that connect to a computer. Suggested probes include a Force Plate for students to stand on and a low-g accelerometer. Students should have a basic understanding of what a Free Body Diagram is and the connection between Force and acceleration. It would be hard to perform this activity without the computer or computer software, although it could be performed as a class demonstration if instructors only had access to one computer and one set of probeware.

**Subject**: Physics:Classical Mechanics

**Resource Type**: Activities:Lab Activity

**Grade Level**: High School (9-12)

## Description and Teaching Materials

The attached Lab Sheet guides the students through the lab activity. The school must have an elevator available to them. Students will need a computer, computer interface and a force plate probe as well as an accelerometer. Students are led through the analysis of an elevator ride and asked to complete a handout of calculations and diagrams. Closure activities would include turning in the completed lab sheet and discussing the results afterward, and giving them another example of a graph to draw such as What will the Force vs time graph look like for the following motion: A student stays off of the force plate for 2 seconds, steps on to the force plate for 2 seconds, scrunches, jumps, lands, stays on for 2 seconds and then steps off for two seconds. Lab Handout for students and instructors (Microsoft Word 274kB Sep25 07)

## Teaching Notes and Tips

Be sure to have the students hold the accelerometer against the wall of the elevator. It helps to have them hold it against something such as a railing for support. Let others in the building know that your students will be riding the elevator that day. This activity is different because I am having the students predict what they believe the graph will look like, and then they need to really analyze the situations and the graphs they obtain. It is a real life example of a force vs time graph that they can actually feel and visualize!

## Assessment

Students will complete the lab handout provided to them for instructor assessment and feedback. The instructor will also have a formative assessment the next day with another scenario as stated above in the activity description to check for student understanding.

## Standards

9-12.II.D.1 - Newton's Laws of motion