Physics Project ProposalFeb.,2003

TopicExpected outcome/resultsExperimental workTheoretical backgroundScheludeProblems encountered

Choosing a topic

Related to the physics already learned, or going to learn laterBoth theory and experiment involved (or craft-work, model-making instead)Not too complicated, easily to be understood

Choosing a topic – example

Study the period of an interrupted pendulum

(ref: Physics Teacher, 40, p.476)

Area: SHM

length, L

peg

Ls

h

What you expect to find?

Make use of apparatus to measure physical quantities: period (T), lengths (L, Ls, h,… etc.)

Describe how T depends on L, or Ls.

Find the relationship between some quantities, say T=T(Ls) or T(h).

See what is deviated from theory.

What you expect to find?

Plot graphs, say T vs Ls, or T vs h.

Compare with well-known results:

Try to explain some observation in the experimental result. Also point out the new knowledge, if any.

g

L2πT

Experimental work

A workable design is very important.Before conduct the experiment, you should ask what apparatus is provided by our physics lab.Try to list procedures and predict what result you will obtain.The lab. work should be as simple, clear as possible.

Experiment – example

Apparatus: string, clamp & stand, copper bob, stop watchProcedures: the same as we did in practical sessions.Expected measurement: – (1) period for diff. Ls (w/ h constant)

– (2) period for diff. H (w/ Ls unchanged)

Experiment – setup

The pegLs

Experiment – demonstration

Theoretical background

Search possible backup from textbook, literature, web-sites, etc.Sort out those information you can understand and easier to be received by your classmates.Try, based on your research, formulate a theoretical basis for your project.

Theoretical background

If you have confidence, try to understand what results obtained from your experiment. Then, work out your own theory and show/suggest your conclusion or any prediction.

Well, you are a physicist in SWCSSS!

Theory – example

From the paper, we have, T0 = period w/o the peg. A computer calculation is shown. As mentioned in textbook, the result is not so simple, while is larger than 30o. Check it!

L

L

T

T s121

0

Theoretical calculation

0.5

0.6

0.7

0.8

0.9

1

0 0.2 0.4 0.6 0.8 1

1數列

2數列

T/T0

Ls/L

Result 1 – T in simple pendulum formula;Result 2 – T is corrected to 2nd order for large amplitude

Comparison w/ theory – 1Comparison of ex-T/T0 to th-T/t0

0.500

0.600

0.700

0.800

0.900

1.000

0.000 0.200 0.400 0.600 0.800 1.000

Ls/L

T/T

0

1數列 2數列Result 1 – T/T0 in experimental work

Result 2 – T/T0 by theory with large amplitude

Comparison w/ theory – 2

Result 1 – Measurement of T/T0 with h, in experimental workResult 2 – Calculation of ratio of T/T0 with h

0.850

0.870

0.890

0.910

0.930

0 0.1 0.2 0.3 0.4 0.5 0.6

1數列

2數列

Comparison w/ theory – 3

A plot of log(2(T/T0)-1) vs log(Ls/L), as shown.

-0.6

-0.5

-0.4

-0.3

-0.2

-0.1

0-1.2 -1 -0.8 -0.6 -0.4 -0.2 0

From the graph,

y=0.2, x=0.4

Slope = 0.2/0.4 = 0.5

Theoretical value of the slope = 0.5!

Schelude

20/02-25/04 Formulate the proposal with detail,make a good plan, info-review

May-June Experimental design, search from books/literature, theory/calculation

Summer Vocation

Field work: perform your experiment, computer-calculation, etc.

Second Year (September)

Written report, oral presentation of your finding

Problem encountered

Only traditional apparatus is provided by the lab. So, measurement may be not accurate. Mathematical basis is not enough to formulate a model for “large amplitde” oscillation.