New The University of Utah - Giving Scientific Presentationsbelz/phys6719/presentations.pdf ·...
Transcript of New The University of Utah - Giving Scientific Presentationsbelz/phys6719/presentations.pdf ·...
Giving Scientific Presentations
JB20120403
Prologue: Giving Bad Talks
Topics
● General guidelines● Miscellaneous advice● Sample presentation
General Guidelines
● 10-12 minutes, w/ 3 minutes Q & A
– Questions mandatory!● Save Powerpoint, Open Office Impress, et cetera
presentations in .pdf format
– Give HM and JB an electronic copy in advance● Choose within lab teams who will talk on which
experiment.● Please arrange a meeting with HM/JB (as
appropriate) to review your talk.
General Guidelines
● Talks should follow this rough outline:
– Title Page (1 slide)– Intro (background and theory) (~1-2 slides)– Experimental Method (~2-3 slides)– Data and Analysis (~2-3 slides)– Discussion (~1-2 slides)– Conclusion (1 slide)
Miscellaneous Advice
● Graphics– Readable– Balance text and figures
● Be aware of time– Overall length of presentation– Remember – multiple input paths– About one minute per slide– Rehearse!
● Nervousness
Sample Presentation
Measurement of the Acceleration Due to Gravity
John BelzApril 3, 2012
Outline
● Acceleration due to gravity● Method: The simple pendulum● Description of data analysis● Discussion of results● Concluding remarks
Background● Galileo asserted that in the
absence of air resistance all objects fall with the same constant acceleration.
● More recent experiments have confirmed this to an accuracy of a few parts in a billion:
– S. Carusotto et al., Phys. Rev. Lett. (1992).
– S. Chu et al., Nature (1999).
● What is this acceleration g?
Measuring g; Free-Fall Experiments
● Measure distance fallen over some time interval
● d = ½ gt2
● Difficulties:– Precise
measurement of distance
– Wind resistance becomes significant
Measuring g; Pendulum Experiments
● The period of oscillation is dependent on g
● Air resistance negligible
● Random error can be controlled by measuring over many oscillations.
The Simple Pendulum
Data and Analysis
● Measure with a stopwatch the time it takes for the pendulum to complete 20 oscillations. Do this ten times, and take the average to find the period T of oscillation.
● Do this for several values of the length l.● Plot l versus T2, and g is proportional to
the slope.
Experimental Data
● Result of averaging over 10 20-oscillation trials.
Linearize and Fit to Extract g
● Perform weighted linear least-squares fit to determine slope
● Best fit gives g = 979.3 ± 3.0 cm/s2
● 2 = 4.79, 3 D.O.F.
● p-value = 0.19. Model is supported by the data.
Discussion● Good agreement with
linear l vs T2 model
● Residuals indicate random error well understood, no significant systematic effects at this level.
● Uncertainty in length dominates; longer pendulum would have better error in relative height.
● Averaging over more periods can improve timing uncertainty.
Conclusion
● The simple pendulum is a useful tool for measuring the acceleration due to gravity.
● Measured g = 979.3 ± 3.0 cm/sec2
● Suggested improvements to random and systematic uncertainties have the potential to improve precision of result.
Schedule
● Tues 3rd April: This lecture● Fri 6th April: Complete Lab #3● Fri 13th April: Submit Lab #3 reports● Mon 9th – Mon 16th April: Arrange meeting
with instructor to review presentation. ● Tues 17th April: Oral Presentations