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Forces and Motion

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. 

Newton’s Third Law Experiment with Crash Cushions

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Submitted by PocketLab on Wed, 02/06/2019 - 18:44

Engineering Crash Cushions to Learn Newton's Third Law

Newton's Third Law Example

Car crashes are a dangerous example of Newton's Third Law. The car exerts a large force on the wall and the wall then exerts a large force back onto the car. Civil engineers are always trying to think of new ways to make highways safer. Building crash cushions along highways that reduce the impact force of the collision will, according to Newton's Third Law, also reduce force experienced by the passengers of the car. This can save lives.

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How does a Pressure Sensor Work - Physics of Probeware

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

Introduction to Pressure Sensors

Pressure sensors are one of the most widely used sensors and can be found in probeware for lab measurements, but more commonly in billions of devices including smartphones, wearables, automobiles, drones, weather centers, and medical instruments. Pressure sensors were one of the first sensors to be miniaturized and mass produced at a low cost through microelectromechanical systems (MEMS) fabrication.

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How to teach NGSS MS-PS2-1: Newton's Third Law

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Submitted by PocketLab on Wed, 02/06/2019 - 00:19

Using PocketLab to Teach MS-PS2-1: Engineering Design and Newton's Third Law

NGSS Standard MS-PS2-1: What's in the standard?

Teaching NGSS Standard MS-PS2-1 can have challenges. Students need to apply principles in forces and motion to engineer a design that will solve a problem. The performance expectation for the standard states: Apply Newton’s Third Law to design a solution to a problem involving the motion of two colliding objects.

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