To Measure the Constant Velocity of a Trolley using a Ticker Timer and Ticker Tape.

Materials Used:

  • Runway
  • A Trolley
  • A ticker timer and ticker tape
  • Power Supply

Procedure:

  1. Set up apparatus as shown in the diagram.
  2. Dust the runway to prevent friction during experiment.
  3. Raise the runway by placing books underneath the end where the ticker timer is placed. We do this to negate friction. Adjust height of runway until the trolley is seen to move at constant velocity when given a gentle push.
  4. Ensure there is sufficient ticker tape and attach to trolley.
  5. Turn on the ticker tape timer and give the trolley a gentle push.
  6. Stop the trolley and switch off the timer.
  7. Remove the ticker tape. It should have a series of equally spaced dots printed on the tape. If not you may need to adjust the height of the runway.
  8. Measure and record the distance between ten spaces near the starting point but ignoring the first few dots’ as this was where you gave it a gentle push. Initial Velocity, U, can be found by

Velocity = Distance / Time

We take the time to be 0.2 as we measure ten spaces, therefore 10/50 as there are ten dots produced per second.

  1. Now measure and record the distance between ten spaces near the end of the tape just before you stopped the trolley. Final Velocity, V, can be found by

Velocity = Distance / Time

We take the time to be 0.2 as we measure ten spaces, therefore 10/50 as there are ten dots produced per second.

  1. By showing U = V, we show that we have constant velocity.
  2. Repeat experiment with the trolley travelling at different velocities.

Formula-

Result:

The Velocity at beginning (u) should equal the velocity at the ending (v).

If u=v therefore the experiment has shown there is constant velocity.

Most Frequently Asked Questions on this Experiment;

  • Why is the runway raised at one end? This is to negate friction during experiment.
  • How do you know it is raised to the correct height? As the trolley will seem to be moving at a constant velocity.
  • If the dots are not evenly spaced what do we know about the velocity?How can we change this? We know that the trolley is not travelling at a constant velocity and we can change this by either raising or lowering the runway.
  • How do we prevent gravity from acting on the experiment? By ensuring constant velocity.

Precautions:

  • Dust the runway to reduce friction.
  • Have plently of slack on the ticker tape so as not to interrupt the tape running smoothly thought the timer.
  • Use a friction less trolley (the wheels run very smoothly).
  • Give the trolley a very slight to start it down the run way.
  • Negate the first and last few dots when calculating the velocity.
  • Use 10 spaces (or 11 dots) as the distance in the formula v = d/t
  • The time between each dot is 0.02 s, because the a.c. supply is 50Hz (therefore strikes the tape 50 times per second, or 0.02 between each dot). Therefore the time between 11 dots is 0.2 (0.02 x 10).
  • To negate the effects of gravity raise the runway to get a constant velocity.

Mistakes:

  • Students don’t use 0.2 as the time between 10 spaces.
  • They forget to negate the first and last few dots.