Physics

PocketLab Investigation of Fuel Efficiency

Submitted by Rich on Wed, 06/28/2017 - 02:56

With gas prices as high as they are and having a growing concern for the environment, Americans today are becoming conscious about things they can do to improve fuel efficiency.  Many realize that driving at the posted speed limits promotes both safety and reduces the rate at which fuel is consumed.  With these things in mind, some have purchased hybrid vehicles including the Toyota Prius, all-electric vehicles such as the Nissan LEAF, or range-extending vehicles such as the Chevy Volt.  Those with EV's soon realize that they get more miles per charge if they avoid driving at excessively hi

The Inverse Cube Law for a Neodymium Dipole Magnet

Submitted by Rich on Wed, 06/28/2017 - 02:31

PocketLab makes is quite easy to investigate and verify the inverse cube law for the magnetic field of a neodymium magnet as a function of distance from the magnet.  All that is needed in addition to The PocketLab is a centimeter ruler, small neodymium magnet, a small block of wood and a little double stick tape.  The photo below shows how the neodymium magnet is taped to the block of wood with the magnet located at the 10 cm mark on the NSTA ruler.  The height of the center of the magnet is at about the height of the circuit board inside of PocketLab.  The X on the front face of PocketLab

Investigating Ampere's Law for a Long Current Carrying Wire

Submitted by Rich on Wed, 06/28/2017 - 02:18

One of the classes of problems dealing with magnetic fields concerns the production of a magnetic field by a current-carrying conductor or by moving charges.  It was Oersted who discovered back in the early 1800's that currents produce magnetic effects. The quantitative relationship between the magnetic field strength and the current was later embodied in Ampere's Law, an extension of which made by Maxwell is one of the four basic equations of electromagnetism.

Magnetic Field on the Axis of a Current Loop

Submitted by Rich on Wed, 06/28/2017 - 02:07

In this lesson students will find that a current-carrying loop can be regarded as a magnetic dipole, as it generates a magnetic field for points on its axis.  The figure below shows a diagram and the equation for the magnetic field B.  Derivation of this equation requries knowledge of the Biot-Savart Law, calculus and trigonometry.  But in this lesson we are interested only in comparing experimental results from PocketLab's magnetometer to the theoretical equation in the figure below.  More advanced students can consider derivation of the equation, if they wish.

Negative Exponentially Damped Harmonic Motion from a PocketLab Pendulum

Submitted by Rich on Wed, 06/28/2017 - 01:02

This experiment allows one to do a quantitative investigation of the damped harmonic motion of a swinging pendulum.  The pendulum is a piece of wood about a yard long from a Michael's hobby shop one end of which has been attached to a PocketLab by a rubber band.  The other end is taped to the top of a doorway, allowing the resultant pendulum to swing back-and-forth as shown in the image below.

PocketLab on an Oscillating Cart

Submitted by Rich on Wed, 06/28/2017 - 00:57

An oscillating cart with a PocketLab provides an interesting way to study Newton's Second Law of Motion as well as some principles of damped harmonic motion.  The apparatus setup is shown in the figure below.  The small dynamics cart that can quickly be made from parts included in the PocketLab Maker Kit is shown in its equilibrium position.  Rubber bands are attached to each side of the cart and to two ring stands weighted down with some heavy books.  It is best to use rubber bands that provide as small Newton/meter as possible.  PocketLab is attached to the cart with its x-axis parallel t

Quantitative Experiment to Determine the Relationship Between a Pendulum's Length and Period

Submitted by Rich on Wed, 06/28/2017 - 00:49

PocketLab is a perfect device for determining the quantitative relationship between the length of a pendulum and its period of oscillation.  Pendulums of known lengths were made from balsa wood strips such as those available from Michaels and other hobby stores.  The photo below shows six such pendulums of lengths 15, 30, 45, 60, 75, and 90 cm alongside a meter stick.  The picture shows that PocketLab was taped with double-stick mounting tape to the pendulum whose length is 45 cm.

Acceleration is Proportional to the Square of the Velocity and Inversely Proportional to Radius

Submitted by Rich on Mon, 06/26/2017 - 18:35

PocketLab in conjunction with a 33-45-78 RPM turntable is an ideal setup for studying centripetal acceleration.  There are two videos that can be found in the Videos page of this web site.  They show that (1)  keeping radius constant implies that centripetal acceleration is proportional to the square of the velocity, (2) keeping velocity constant while varying the radius implies that centripetal acceleration is inversely proportional to the radius.

Determining the Radius of Curvature of a Gradual Street Turn

Submitted by Rich on Mon, 06/26/2017 - 18:07

This lesson is a physics application of PocketLab that allows students to determine the radius of curvature of a gradual turn on a street.  A PocketLab mounted on the dashboard of a car records both the angular velocity and the centripetal acceleration of the car as it moves at a nearly constant speed around the curve.  All of the required data for an example problem are contained in files attached to this lesson.  Alternately, students can collect their own data.  If the latter approach is used, students should be cautioned to be safe: (1) follow all speed limits and traffic laws, and (2)