# Measurement of Velocity and Acceleration

In this experiment a trolley is allowed to roll down a runway which is tilted at an angle. The runway must first be tilted to overcome the friction in the wheels of the trolley. A ticker tape timer is used to measure the velocity near the start of its journey (u) and near the end(v). The acceleration can then be calculated. Note: In this simulation the angle of the runway can be changed by dragging the slider right or left.

Procedure:
1. Using the slider below the simulation, raise the runway a few degrees.

2. Press "Release Trolley". If the trolley does not move raise the runway a little more and try "Release Trolley" again. When friction is overcome the trolley accelerates very slowly. In the lab, at a slightly lower angle, a little push would make it move with constant velocity.

3. Press "Get Tape and Ruler".

4. Measure and record a five-space distance (5/50 s) near the start

5. Calculate "u" = distance/0.1. Calculate "v" in a similar way near the end of the tape

6. Calculate the acceleration using the formula a = (v - u) / t where t is the number of dots from start of u interval to start of v interval / 50.

7. Press reset and try different angles

Note:Because of the small space available the accelerations calculated in this simulation are much too large.
Precautions:

• Ensure that the runway in smooth, free of dust, and does not sag in the middle
• At constant velocity the dots must be equally spaced all along the tape (same distance for each 1/50th. sec.). Not possible with this simulation.
• Ignore the first few dots on the tape. These are unreliable and too close together for accurate measurement.
• Place a ruler right on top of the tape with eye directly above when measuring distances to avoid parallax errors

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