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How does a Rangefinder Work - Physics of Probeware

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Submitted by clifton on Tue, 02/19/2019 - 04:34

Introduction to Rangefinders

Rangefinders, sometimes called motion sensors or motion detectors are commonly used in probeware, camera autofocus, and robotics. Rangefinders operate on the principle of a time-of-flight measurement and consist of a transmitter and receiver. The transmitter emits a signal (ultrasonic or optical) then the receiver detects the reflection or echo of the signal. The amount of time between transmit and receive is called the time-of-flight and is used to calculate the distance to the reflecting object:

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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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Thermal Energy Particle Motion Experiment

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Submitted by PocketLab on Sat, 02/09/2019 - 00:28

How does adding thermal energy affect the particle motion of a gas? 

NGSS Alignment: MS-PS3-4

The disciplinary core idea behind this standard is PS3.A: Definitions of Energy and PS3.B: Conservation fo Energy and Energy Transfer. In PS3 the standard specifically looks at how temperature is a measure of the average kinetic energy of the particles of matter. This leads to the conclusion that the temperature and the total energy of a system depend on the type, states, and the amounts of matter present.

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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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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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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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