060929

Problem Number 1

Give an example of a situation in which you are given a, Ds and Dt, and reason out all possible conclusions that could be drawn from these three quantities, assuming uniform acceleration. Accompany your explanation with graphs and flow diagrams. Show how to generalize your result to obtain the symbolic expressions for v0 and vf.

 From `ds and `dt you get vAve = `ds / `dt.

From a and `dt you get `dv = a * `dt.

From a v vs. t graph you see that half the change in velocity occurs before the midpoint clock time, and half after the midpoint clock time.  Since vAve occurs at the midpoint clock time, it follows that

v0 = vAve – ½ `dv = `ds / `dt - ½ (a * `dt) ) and

vf = vAve + ½ `dv = `ds / `dt + ½ (a * `dt) ).

Problem Number 1

Give an example of a situation in which you are given v0, vf and Dt, and reason out all possible conclusions that could be drawn from these three quantities, assuming uniform acceleration. Accompany your explanation with graphs and flow diagrams. Show how to generalize your result to obtain the symbolic expressions for Ds and a.

From v0 and vf you get vAve = (vf + v0) / 2, since acceleration is constant.

From v0 and vf you get `dv = vf – v0.

From vAve and `dt you get

`ds = vAve * `dt = (vf + v0) / 2 * `dt.

From `dv and `dt you get

a = `dv / `dt = (vf – v0) / `dt.

Force Experiment 1

Get a scale reading for the rubber band chain while it holds 1 domino.  Repeat for 3, then 5, then 7, then 9 dominoes.

Take the data that will allow you to figure out the actual length of the rubber bands in the chain for the 1-domino case.

Graph the number of dominoes vs. the scale reading..

Explain how you would convert this graph to a graph of the number of dominoes vs. the length of the chain, and also into a graph of number of dominoes vs. the total length of the rubber bands.

Using your graph, predict the scale readings for 2, 4, 6, 8 and 10 dominoes.  Give the length of the chain for each of these readings.  Give also the total length of the rubber bands for these readings.

Do the TIMER experiment:

Downloading the TIMER program:

Log in to Blackboard at bb.vccs.edu using username vhstudent and password vhstudent.

Click on the 'course' Supervised Study Supervised Study.

Click on Course Documents.

The second item down is entitled q_a_prelim.  Under that heading is a program entitled 'create vhmthphy'.  Run that program; this only takes a couple of seconds.

Scroll down the Blackboard page to Course Documents.

Scroll down that page to Physics I.

Scroll down until you find the heading 'TIMER program'.

Save the program to the desktop or any other convenient location.

Go to http://www.vhcc.edu/dsmith/forms/ph1_timer_experiment.htm.  If you didn't obtain your data in class, you should simply fill in the form according to instructions on the form, and submit it.  If you did obtain your data in class, you will need to follow the instructions on the form it was handed out in class.  You also have the option of simply completing the form online, which you might find quicker and more convenient.