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Physics IA / Ver. / 0.21
Last updated / 02.01.02

Impulse

Syllabus reference / 2.7
Assessment Criteria / Data Processing and Presentation, Evaluation
Date delivered out
Date for handing in
Aim / Investigate if the change in momentum for an object is equal to the impulse given.

Equipment

TI-calculator with link cable and CBL, ultrasonic motion detector, student force sensor, wagon, tread with elastic band, tape, scale

Procedure

Use a screw holder to fasten the force sensor to the end of the table. Connect the tread with the elastic band to the wagon and the force sensor, so that the wagon is stopped by the tread when you push it along the table. The purpose of the elastic band is to increase the duration of the applied force.

Use tape to fasten the motion detector to the table 60 cm from the where the wagon stops, so that the detector will measure the distance to the wagon before, during and after the bounce.

Connect both the motion detector and the force sensor to the CBL. Fasten a bit of cardboard to the wagon to improve the reflection of the sound pulses from the detector.

Data collection

The force sensor must be calibrated with the appropriate procedure provided in the PHYSICS program on your calculator. Set up the probes with 0.02s between the 100 samples, which give the experiment a total length of 2s.

Start the data logger and put the wagon into motion towards the motion detector immediately.

Try several times until you get a graph with maximum around t = 1s.

Determine the mass of the wagon.

Transfer your data to Graphical analysis (only L1(time), L2(force) and L4(position)).

Repeat the experiment so everybody on your group gets their own data to analyse.

Data analysis

Plot a scatter diagram of the force versus time (remember to use correct quantity symbols and units). Find the impulse from the area under the graph (mark the area and use integral from the analyse menu).

Plot a scatter diagram of the position as a function of time. Find the velocity of the wagon just before and after the bounce (a helpful hint: let the marking of the area still be on when you change from the force to the position graph.). To find the velocities you could either use the tangent line from the analyse menu or you could fit linear curves to the points in question.

Use these results to find the change in momentum for the wagon. Compare this to the impulse found earlier.

Questions

Which other forces act on the wagon during the deceleration of the wagon?

How would these forces affect the value for change in momentum?

How would the force-time graph look like if you only used the tread without the elastic band?

Will the tension measured by the force sensor be the same as the tension acting on the wagon?

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