Momentum conservation experiments in physics have a reputation for taking a lot of space to perform—more space than students typically have available. Did you know the new Vernier Motion Detector lets you easily perform a collision experiment with the Vernier Dynamics System track and a couple of Vernier carts?

Combining the 15 cm minimum distance of the new Motion Detector with the 1.2 m track makes for a nice, compact momentum-conservation activity.

We set up the track with a Motion Detector just a few centimeters from each end. In Logger Pro®, the direction of one detector was reversed, and then both detectors were zeroed with the carts temporarily stuck together near the middle of the track. This places the origin of the common coordinate system near the middle, and the two readings will then be the same when the carts are in contact.

In order to create completely inelastic collisions, the Vernier carts include Velcro® end caps. After starting data collection, we waited a moment, and then rolled the carts toward one another, with one cart moving a bit faster than the other. On collision, the Velcro held the carts together as they rolled on.

Note several features of the graph:

• Before the collision, the carts are moving with constant velocities of opposite sign, since they are moving toward one another.
• The carts move as a unit after the collision with a common, constant velocity.

Each cart is nearly 0.500 kg; the total momentum before the collision is then 0.184 kg m/s. Afterward, the momentum as 0.183 kg m/s.

Chemistry teachers will like this new Vernier product. The Stir Station is a high-quality, multi-function magnetic stirrer. The Stir Station

• Uses a closed-loop speed control, thus making it easier than other models to fine tune its stirring speed (50-1250 RPM).
• Has a stirring platform that is lit with three white, cool LED bulbs.
• Includes a removable ring stand post conveniently positioned and affixed to the stirrer base, at a distance that will easily accommodate most buret or utility clamps.
• Runs on either AC power (adapter included) or four C batteries (not included).

Vernier Stir Station

Order Code STIR

$119

The adage “a picture is worth a thousand words” takes on new meaning with the addition of the ProScope to Vernier’s line of data-collection tools. This digital microscope connects directly to the USB port on your computer and makes it easy to magnify and examine objects on your Macintosh or PC computer screen. The built–in white LEDs light specimens, and the ProScope is completely powered from the computer’s USB port. The included USB Shot software allows you to capture still images, time-lapse photography, or QuickTime™ movies.

The basic 50x lens is perfect for a wide variety of uses. Additional interchangeable lenses (sold separately) provide the ProScope with tremendous versatility. The C-mount adapter allows you to connect to traditional microscopes for even more magnification.

The best part about the ProScope is that Logger Pro 3.4 (available this summer) will allow you to capture time lapse images and sensor data simultaneously!

The ProScope can be used for many exciting lab activities:

• Reinforce the concept of friction. Examine the roughness of various surfaces and correlate to friction measurements.
• View the formation of gas bubbles during a reaction between hydrogen peroxide and potato catalase.
• Examine water samples for algae, animals, and other life during water quality studies.

The ProScope is available separately with an assortment of lenses or as part of the new Science CSI Kit. Activities for the ProScope can be downloaded for free from www.vernier.com/proscope.

ProScope image of soil taken with a 50x lens

Scoping out the anthers and stigma of a daffodil

Basic ProScope Kit (with 50x lens)	Order Code BD-PSB	$219
Complete ProScope Kit	Order Code BD-PSC	$750
Science CSI Kit	Order Code BD-CSI	$999