• Motion Encoder Cart
• Motion Encoder Receiver
• Motion Encoder Long Track Strip for application to 1.2 m or 2.2 m track
• Dynamics Cart and Track System Fasteners for Force Sensor and Accelerometer
• Magnetic and hook-and-pile end caps
• Allen wrench

The Motion Encoder Transmitter requires two AAA batteries (not included).

Please see the following link for platform-specific connection information:

www.vernier.com/start/dts-mec

Motion Encoder Strip Application

The track must have an encoder strip applied for the cart to determine its motion. The strip is applied immediately next to the center slot, between the slot and the numeric scale on the top surface of the track.

1. Clean the track surface with a damp cloth and allow it to dry.
2. If applying the strip to a 1.2 meter track, cut the strip into to ~1.2 m pieces.
3. Pull about 10 cm of backing off of the strip.
4. Align the strip next to the center slot, within 1 cm of the track end. The strip need not extend all the way to the end of the track, but it can.
5. Carefully press down the strip, working your way along the track and removing the backing as you go. Keep the strip edge right next to, but not hanging over, the center slot. Do not stretch the strip.
6. Remove the rest of the backing, and press the strip down on the full length of the track.
7. Trim any excess strip from the track end.

If you are adding a second strip to a track that already has a strip in place, apply the strip to the other side of the center slot. This will allow you to use two encoder systems on the same track.

No calibration of the Motion Encoder Cart and Receiver is necessary. The printed bars on the track determine the scale, and the cart encoder counts the passage of the bars. Available units are meters and feet, selectable in the software.

In contrast, it is possible and desirable to zero the encoder. Unlike an ultrasonic motion detector, there is no way for the system to have an unchanging reference position; it can only count bars from the point at which the encoder cart is placed on the track. As a result you may want to move the cart to the receiver end of the track and zero the reading in software.

The positive direction can be reversed, so that readings increase as the encoder cart moves toward the receiver. A reversed coordinate system is helpful when using two Motion Encoder Systems to monitor the motion of two encoder carts, so that the positive direction is the same in both cases.

Because the encoder strip must be continuous, the optical motion encoder cannot be used with a Track-to-Track Coupler (order code T2T-VDS).

1. Attach the receiver to the end of the track, matching the encoder strip on the track to the markings on the receiver.
2. Place the track on a level surface.
3. Insert two AAA batteries (not included) into the encoder cart.
4. If your are using a 2.2 meter track, adjust the cart’s range setting to the 2 m power level. The switch is located in the encoder cart’s battery compartment.
5. Connect the receiver to an interface such as a LabQuest^® 3. If using a computer or Chromebook, connect the interface to your device, then launch Vernier Graphical Analysis^®.
6. Turn on the cart by pressing the power button. It will glow blue when the cart is on.
7. Place the cart on the track, wheels in grooves, with the blue light facing the receiver.
8. Begin data collection, and let the cart roll.

Use of Two Vernier Motion Encoder Systems on the Same Track

Some experiments require measuring the motion of two carts. This can be done by adding a second Motion Encoder Cart and Receiver. A Motion Encoder Receiver is placed at either end of the track, and two Motion Encoder Carts are used on the track, each with its transmitter facing the unobstructed receiver. A second encoder strip must be applied to the track, one on either side of the center slot.

Consider reversing the direction of one receiver so that the same direction is positive for each system. Put the carts together, and zero both systems. This will put the carts on the same coordinate system; if they move together in contact, their position readings will be the same.

Use of Multiple Vernier Motion Encoder Systems in the Same Room

Because of the narrow IR beam used for signaling between the cart and receiver, interference should be rare. However, if one apparatus is interfering with another, the problem can be resolved by repositioning one of the tracks.

All Motion Encoder Carts are interchangeable; that is, there is no matching of cart to receiver.

The Motion Encoder Cart requires two AAA batteries. Either NiMH rechargeable batteries or alkaline disposable batteries can be used. The receiver is powered by the interface.

Turn on the cart by pressing the clear power button on the cart endcap. It will glow blue when power is on. Press again to turn off. The cart will turn itself off after 20 minutes of inactivity. Any motion on the track will cause the timer to reset.

Battery life depends on use and the range setting. Low battery levels may cause erratic detection of the cart motion, including incorrect velocity signs. Replace the batteries if this is seen.

Measurement range 1 m range 2 m range	1.2 m track 2.2 m track
Position resolution	1 mm
Maxim useful data-collection rate	30 Hz

Do not wrap the cable tightly around the sensor for storage. Repeatedly doing so can irreparably damage the wires and is not covered under warranty.

The Vernier Motion Encoder System can be used wherever a Motion Detector could have been used with a cart and track. The encoder depends on the presence of the track, so only cart and track experiments can be performed.

Measure Cart Acceleration

The basic motion of a cart on a ramp can be studied. For example, perform Experiment 3 from Physics with Vernier, “Cart on a Ramp.” Or, repeat Galileo’s experiment of determining g using an object and a ramp. This is Experiment 4 “Determining g on an Incline” from Physics with Vernier.

Newton’s Second Law

Use a force sensor on the encoder cart to record both applied force and acceleration. The two will be proportional. Or, set up a half-Atwood machine with a hanging mass and a pulley at the track end opposite the receiver. Measure the acceleration of the encoder cart as a function of the hanging mass.

Measure Fan Cart Acceleration

Add a Cart Fan (order code DTS-CFAN) or an Encoder Fan Cart (order code CART-FEC) to observe the motion of a cart under constant thrust.

Measure Cart Acceleration with Friction

Add a Friction Pad (order code DTS-PAD) to the encoder cart and observe the motion of the cart with varying frictional forces.

Momentum-Impulse

Add a force sensor and a Bumper-Launcher Kit (order code BLK) to observe the relationship between momentum and impulse. Find the impulse by integrating under a force vs. time graph.

Conservation of Energy

Use two Vernier Motion Encoder Systems to observe a change in energy due to a collision between two carts.

Conservation of Momentum

Use two Vernier Motion Encoder Systems to observe a change in momentum due to a collision between two carts. Try different kinds of collision: elastic, inelastic, totally inelastic.

Range Setting

For troubleshooting and FAQs, see www.vernier.com/til/3153

Vernier Dynamics System (order code DTS)

Vernier Dynamics Cart and Track System is a low-friction anodized 1.2 m track and optics bench combination designed for kinematics, dynamics, and optics experiments. It includes two carts.

Vernier Dynamics Cart and Track System with Long Track (order code DTS-LONG)

The long version of the Vernier Dynamics Cart and Track System includes a
2.2 m track instead of the 1.2 standard track.

Track (order code TRACK)

The Combination 1.2 m Track/Optics Bench comes with the Encoder System Strip installed.

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