Lab Five Energy

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Lab Assignment 5: Energy

Instructor’s Overview

Energy is a key concept in physics. In this lab we will explore the concepts of potential and kinetic energy and energy conversion. In the first part of the lab, we will use a rubber “popper” to directly experiment with energy. We’ll next study a hypothetical roller coaster and investigate it’s conversions of potential and kinetic energy.

This activity is based on Lab 11 of the eScience Lab kit.

Our lab consists of two main components. These components are described in detail in the eScience manual. Here is a quick overview:

  • • In the first part of the lab, you will work with a rubber popper to explore concepts such as potential energy, kinetic energy, and energy conservation.
  • • In the second part of the lab, you will be presented with a diagram of a rollercoaster. Based on your knowledge of potential and kinetic energy and energy conservation, you will answer a series of questions on the design. This activity dovetails well with the Instructor’s Commentary on roller coasters.

Take detailed notes as you perform the experiment and fill out the sections below. This document serves as your lab report. Please include detailed descriptions of your experimental methods and observations. Record all of your data in the table that is provided in this document.

Procedure 1 – Popper Experiment:

  • • Place the popper on a smooth flat surface like a linoleum floor. I recommend placing the popper on the floor since it travels a good height. When I initially ran the experiment on my kitchen table, the popper hit the ceiling.
  • • I recommend recruiting a lab assistant when you run the popper experiment. When you turn the popper inside out and place it on the ground, it takes off in short order. I recommend having one person holding the popper on the floor and that person also timing the flight. The other person should be standing and ready to place their hand at the peak of the flight.

Student:

Abstract

Material and Methods

Results

Data tables for the popper experiment:

Maximum height test

Trial

Height (meters)

1

2

3

4

5

6

7

8

9

10

Average

Standard Deviation

Flight time test

Trial

Total flight time (seconds)

1

2

3

4

5

6

7

8

9

10

Average

Standard Deviation

Analysis and Discussion

Based on your results from the popper energy experiment, please answer the following questions:

  1. 1. What is the gravitational potential energy of the popper at its average measured maximum height?

Use g = 9.8 m/s2, and a mass of 0.01 kg.

Potential energy = PE = mgh =

  1. 2. Use the following kinematic equation to calculate the initial velocity of the popper based on how long it is in the air:

v0 = : t is total time of flight (up and down).

n

  1. 3. Use the calculated value for the initial velocity to find the kinetic energy of the popper right as it “pops” up.

KE = ½ mvo2

  1. 4. Compare your answers for potential energy and kinetic energy. Are they the same, or close to the same?
  1. 5. Is the energy stored in the popper rubber before it “pops” more or less than the energy the popper has at its total height? Why?

Roller coaster exercise

Consider the following roller coaster layout taken from the eScience manual:

Based on your understanding of energy concepts, please answer the following questions. Make sure to include detailed physical arguments.

  • • What happens to the roller coasters kinetic energy between points B and C? What happens to its potential energy between these points?
  • • Why is it important for A to be higher than C (assume friction is negligible)?
  • • 125

  • • If the roller coaster starts at point A, can it ever go higher than this point? What causes the roller coaster train to lose energy over its trip?
  • • List the points in order of greatest potential energy to least.

Conclusions

References