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High School

Brownian Motion: Order from Chaos

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Submitted by Rich on Fri, 03/15/2019 - 02:27

Brownian Motion

Brownian motion can be defined as the random motion of particles in a liquid or gas caused by the bombardment from molecules in the containing medium.  Have you ever looked at dust particles in the sunlight shining through a window?  They appear to move about randomly, even defying gravity.  This is an example of Brownian motion in which the dust particles are bombarded on all sides by gas molecules in the air.  Other examples of Brownian motion include the motion of grains of pollen on the surface of still water, the dif

Ideal Gas Law Verified in a Steel Balls Lab

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Submitted by Rich on Tue, 03/05/2019 - 22:18

Introduction to the Ideal Gas Law

The ideal gas law is commonly seen in the form PV = nRT, where P is the pressure, V is the volume, T is the absolute temperature, n is the amount of the gas in moles, and R is the ideal gas constant.  It is a composite form of Boyle's, Charles's, Avogadro's, and Gay Lussac's laws.  This law helps to explain how many things work, including bicycle pumps, hot air balloons, pressure cookers, and steam engines, just to mention a few.

Moment of Inertia Challenge

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Submitted by Rich on Sat, 02/23/2019 - 22:18

Introduction to the Moment of Inertia Challenge

We are going to assume that you have studied the concepts of moment of inertia and physical pendulums in your physics class.  With that in mind, we present a "Moment of Inertia Challenge" for you in this lab.  As you know, moment of inertia depends not only on the mass of an object, but also on how the mass is distributed, as well as the specific axis upon which it rotates.  It is of particular interest to compare the moments of inertia of two objects with the same mass but having the mass dist

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Moment of Inertia vs. Mass

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Submitted by Rich on Sun, 02/17/2019 - 21:06

Introduction to Moment of Inertia

There are numerous analogies when comparing linear and rotational motion.  At the heart of these comparisons lie the concepts of mass on one hand and moment of inertia on the other.  In addition to being a property of any physical object, mass is a measure of the resistance of an object to acceleration when a net force has been applied to the object.  Newton's Second Law of Motion expresses this in the familiar equation F = ma.  By analogy, the moment of inertia of any rigid obj

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Physical Pendulum: Finding Moment of Inertia

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Submitted by Rich on Tue, 02/12/2019 - 18:22

Introduction to the Physical Pendulum

Mount any rigid body such that it can swing in a vertical plane about an axis passing through the body.  You have constructed what is known as a physical pendulum.  The video below shows an example of such a pendulum.  In this video, a rigid circular body is swinging about an axis very close to the edge of the circle.  The circle was cut from a piece of cardboard.  PocketLab Voyager is resting at the bottom of a ring stand directly below the pivot point of the pendulum.  A tiny magnet has been attached to the bottom of the ci

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How to teach NGSS MS-PS2-2: Newton's Second Law

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Submitted by PocketLab on Fri, 02/08/2019 - 18:43

Using a Half-Atwood Machine for Newton's Second Law

The Half-Atwood Machine consists of a cart and a weight connected by a string. It can be a perfect tool for tackling NGSS MS-PS2-2, which is centered around planning an investigation into Newton’s Second Law. Specifically, the standard says: 

Plan an investigation to provide evidence that the change in an object’s motion depends on the sum of the forces on the object and the mass of the object. 

Hysteresis with Rubber Bands

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Submitted by Rich on Wed, 02/06/2019 - 17:49

Introduction to Hysteresis

Hysteresis can be defined as a lag time in the response of a system to forces placed on the system.  The response of the system depends not only on the present magnitude of the force but also on the previous history of the system.  From the point of view of mathematics, the response to the force is a double-valued function.  This means that one value applies when the force is increasing, while another value applies when the force is decreasing.  A graphical plot of force and re

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Rotational Motion: Moment of Inertia

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Submitted by Rich on Thu, 01/24/2019 - 20:05

Rotational Motion and Moment of Inertia Lab Setup

Figure 1 shows a ramp and three distinctly different objects that you will release from rest at the top.  Each object will roll downward to the end of the ramp without slipping, resulting in rotational motion.  The roll of Gorilla tape has a shape known as an annular cylinder.  The can of jellied cranberry sauce is a solid cylinder.  The cardboard tube, in contrast to the can, is hollow.  All three of these objects will rotate about their central cylinder axis while rolling down the ramp.  Each of these three objects has a

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Physics from a Croquet Mallet and Ball

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Submitted by Rich on Sat, 01/19/2019 - 20:23

Introduction

Various forms of the sport now known as croquet have been around for centuries.  Plastic or wooden balls are struck with a mallet through hoops, called wickets in the United States.  The components of a typical croquet set are shown in Figure 1.  Very popular in the UK, there is even a World Croquet Federation for those who take the sport seriously.  In the United States, it is common to set up croquet as a garden game at graduation and birthday parties.  But who would have thought that a croquet ball and mallet equipped with PocketLab Voyager and the PocketL

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PocketLab Voyager: Newton's Law of Cooling

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Submitted by Rich on Thu, 01/03/2019 - 03:02

Newton's Law of Cooling

In this experiment students will use PocketLab Voyager to collect data related to the cooling of a container of hot water as time goes on.  Sir Isaac Newton modeled this process under the assumption that the rate at which heat moves from one object to another is proportional to the difference in temperature between the two objects, i.e., the cooling rate = -k*TempDiff.  In the case of this experiment, the two objects are water and air.

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