Understand Elasticity or Else! Dropping an Egg on the Upper School Head’s Head

By Emily Golding ’14

IMG_0632On January 24th, the 2013-2014 Advanced Physics class  dropped eggs on Dick Bradford’s head. Lucky for Dick, they were attached to a very specific number of rubber bands, calculated by students to drop a precise distance without cracking on Dick’s head. To find this number, we had to understand elastic potential energy and its relation to gravitational potential energy.Relating the equations for these two types of potential energy, after finding the length of one rubber band, the spring DSC07813constant, and the distance from the drop height to the top of Dick’s head allowed us to solve for how many bands would be needed to get an egg as close to Dick’s head as possible without ruining his shirt.

As we had not tested our rubber band ropes with eggs attached, we were duly wary of the imminent danger to the head (pun not intended) of the upper school, and our first trials only came within around 20cm of Dick’s waiting pate. This large amount of error inspired us to to attempt the experiment again, lengthening our bungee cords with additional rubber bands. On the second trial, Dick still remained clean, but our re-calculations successfully brought the eggs well within the danger zone at 2.13cm.

m*g*h = 1/2 * k/n * ( h – nL)^2: Equation we derived relating elastic potential energy and gravitational potential energy.

DSC07781Elastic potential energy: When something elastic, such as a rubber band or spring, is stretched (or compressed), it gains the capacity to perform work. Represented by half of the above equation: =1/2kx^2 (k=spring constant, x=distance stretched/compressed from equilibrium)

DSC07790

Gravitational potential energy: When an object is lifted so as not to be resting on the ground, when you let go, gravity is going to give it the capacity to do work. Represented by the other half of the above equation: =mgh (m=mass, g=gravitational acceleration, h=height from ground)

Spring constant: a number representing how stretchy the rubber bands are. Found with equation: f=kx (f=force applied, x=distance stretched/compressed from equilibrium)

Work: Energy transferred to or from an object by means of a force acting on the object.

Thanks, Dick!

Thanks, Dick!

Students Write How-To’s for Arduino Microcontrollers

An essential part of the Applied Science and Engineering Class is reflecting on the process involved in creating a project in such a way that others can reproduce the project. Honors students in the class created how-to’s using the Instructables Do-It-Yourself (DIY) project-sharing platform.  Collectively, their eleven projects have already received more than 9600 views from Instructables users since they were posted earlier this week–a sign that the students not only created compelling projects, but that their how-tos are easy to follow. One project in particular, How to Do Arduino-Controlled Time-Lapse Photography by Holden Leslie-Bole ’14, was featured by Instructables editors on the homepage. Holden was awarded a free premium membership in recognition of the success of his project.

Students spent three weeks learning how to use and create with Arduinos, single-board microcontrollers that make the use of electronics in multidisciplinary projects more accessible through an open-source electronic prototyping platform.  Projects ranged from Arduino-controlled temperature sensors to a smart heart monitor, to a dubstep piano keyboard. Students kept journals of their process, diagrammed their circuitry, wrote carefully commented code, and gave presentations of their work to conclude the project.

David Otten, course instructor, outlined the goals of the microcontroller project for the students at the outset:

The goal of this project is to learn how to use microcontrollers (hardware and software) and what sorts of applications they are useful for.  To this end, you have been asked to come up with a microcontroller application that interests you.  It must respond to the environment and so should have at least 1 input and 1 output.  Since we have a wide range of experience in the class, the complexity of your project should reflect your skill level.  The focus of this project should be on the circuit and the code (80-90% of your time), not the mechanical aspects – simplify components if you need to (e.g. “this piece of cardboard represents my Levelor blinds” or “this switch represent my toilet flusher”).

Explore their projects here: