4 Lab 4: Momentum and Impulse
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Acknowledgment
This project is made possible with funding by the Government of Ontario and through eCampusOntario’s support of the Virtual Learning Strategy. To learn more about the Virtual Learning Strategy visit: https://vls.ecampusontario.ca.
PHY136 Stay-At-home Experiment 4
Momentum and Impulse
What you will do:
Drop your phone onto a soft surface. Then use the accelerometer that is built in the phone to study the relation between the momentum before a collision and the impulse of the collision.
What you will need:
- A smart phone installed with the Phyphox app
- A soft and inelastic surface (such as a thick blanket)
Demonstration Video: https://youtu.be/3Mrl84QVYNs
Procedures:
- In the Phyphox app, open the “acceleration with g” sensor.
- Start an acceleration with g measurement.
- Hold the phone still for at least 2 seconds at 20 cm above the soft surface with the back of the phone facing vertically down. Then release the phone and let the phone fall onto the soft surface. (If the phone was significantly bounced back by the surface, you should choose a softer surface.)
- Stop the measurement. Among the X/Y/Z acceleration graphs, identify the graph that corresponds to the vertical direction. The largest peak on this graph should be more than 5 times larger than the largest peak on the other graphs. If there is no such graph, repeat the drop while making sure the phone is released flat and then falling onto a flat, soft surface.
- Use the graph of the vertical acceleration to identify the time points at which the phone (a) just got released from the hand, (b) just came in contact with the surface, (c) just reached the maximum displacement into the soft surface.
- Export the data as a csv file.
- Repeat Steps 3 – 6 above for a total of 3 times (keep the dropping height at 20 cm).
- Repeat Steps 3 – 6 above for dropping heights of 30 cm and 40 cm (one drop for each height).
- Use one data set as an example, explain how you determined each time point in Step 5.
- Open any one csv file in Excel. Use the absolute acceleration data in the file to calculate the average gravitational acceleration g of the phone while the phone is stationary. Describe which segment of data were used to compute g.
- In each csv file, create a new column that equals the column of the measured vertical acceleration minus the average gravitational acceleration g (which is obtained in Step 10). The reason for this step is to obtain the acceleration relative to the surface of the Earth.
- In each csv file, select the entire table. Then change the number formatting to show at least 5 decimal places. Save the new csv file for later analysis.
- For each drop, use the Curve Integrator (Python program) provided by the course instructor to calculate (a) the speed of the phone before getting into contact with the surface, and (b) the impulse that the surface applied to the phone before the phone comes to a stop for the first time. (You will n