# Tagged With "Graphs"

Topic

#### PocketLab Joins Ozobot to Study Position, Velocity and Acceleration Concepts

Ozobot ( ozobot.com ) is a tiny one inch diameter line-traveling robot that can be used in conjunction with PocketLab to easily study the physics concepts of position, velocity, and acceleration and their time graphs. PocketLab is simply taped to the top of an Ozobot using double-sided mounting tape. In other words, Ozobot gives Pocket lab a ride. The photo below shows this setup, with Ozobot following a 1/4" heavy black line drawn with a chisel tip marking pen. A magnetic ruler can be...

Blog Post

#### Investigating the "Spinning Coin" (Euler Disk) Problem

Most everyone has spun a coin on its edge on a table top, and many find the result quite fascinating. The coin gradually begins to fall on its side while spinning, makes a whirring sound with increasing frequency the longer it spins, and then abruptly stops. The Swiss physicist, Leonhard Euler, studied this back in the 1700's. An educational toy, referred to as Euler's disk can now be purchased on-line and in hobby shops specializing in science. Such disks have been carefully engineered to...

Comment

#### Re: Investigating the "Spinning Coin" (Euler Disk) Problem

Rich- Your lab made me think of a dynamics problem I had in grad school. I dug up my old textbook so I could share. We analyzed the motion of a similar spinning disk. It was one of the toughest dynamics problems I ever had to solve. You have to solve for a system of equations of the angular acceleration of the spinning disk and the linear acceleration of the disk's center of mass. Eventually the system of equations gets too cumbersome to solve by-hand and so we used a program called...

Comment

#### Re: A Velocity Lab Experiment on Rolling Resistance

Thanks again for the great lesson, Rich!

Blog Post

#### A Velocity Lab Experiment on Rolling Resistance

Rolling resistance is a force that opposes the motion when an object rolls along a surface. In this experiment a coasting cylinder on a carpet gradually slows down and stops due to rolling resistance. The primary factor affecting rolling resistance here is deformation of the carpet as the cylinder rolls. Not all of the energy needed to deform the carpet is recovered when the pressure from the cylinder is removed. In other words, the effect is non-elastic. The purpose of this experiment is...

Blog Post

#### Conservation of Momentum When Two Carts "Explode"

Do you have two carts from the PocketLab Maker Kits? Do you have two PocketLabs? You probably have at least two students in your physics class with iPhones. Do they have the VelocityLap app installed on their iPhones? Then you have the major components for your students to investigate conservation of momentum when two carts on a track "explode". As shown in the picture below, each cart has a PocketLab mounted on one of its wheels, so that the z-axis is the axis of interest when the carts are...