AP Projectile Motion Lab

The lab's purpose was not to find out how far the ball would go. Nor was it to improve your already immense prowess in projectile motion. It was to confirm the concepts and equations we use in calculating projectile motion. Even an error of 5 or even 10% is not so terrible when you consider that the predicted distance was the result of several rough horizontal and vertical measurements and 4 sequential calculations.

Honors

Remember tomorrow is a project day. Be prepared

All classes a=F/M lab

For this lab the force was clearly defined and even calculated for you at the top of the data table for run 1. It is the hanging mass x g = .1 kg x 9.8N/kg ( use 9.8 for labs) =.98 N for Run 1. Force for run2 = .05 kg x 9.8 N/kg = .49 N. The slope you find from your graphs is not force, it is Ma. You were supposed to compare your slope with the force ( .98 N or .49 N depending on the run). If you found your acceleration in cm /s^2 and graphed it without dividing by 100 to get m/s^2 then you need to divide your slope by 100 to compare with the force in N since 1 N is 1 kg m/s^2 NOT 1kg cm/s^2.

Some of you found the force as if the hanging mass were 100 kg instead 100 g = .1 kg. This gives a force that is a factor of 1000 high.

Some of you found the slope and called it the force and then divided it by mass and got your acceleration. This does not prove F= Ma. It proves that Ma/M =a, something that is pretty well established .

To repeat the most important point: you must compare your slope in units of kg m/s^2 with the force ( .98N or .49N) that was accelerating the system.

Honors Practice Test

AP a =F/M Lab

The sentence just before question 5 refers to the timer tape results. Ignore this. Its from when the lab was a much longer affair.

Honors Test

Test Results

Grading them took about 6 hours between AP and Honors because I spent a lot of time trying to figure out what you were trying to do. It looks like we'll be doing some serious reviewing in most classes

Honors

One sign of maturity is taking project assignments seriously. They are even more important than worksheet or text book assignments. For those of you still in the grades before learning mode of thinking, note that project assignments count towards both homework and project grades.

Topic names and logos are overdue in many cases. Hard copies by Monday or zeroes will start show up.

Honors Momentum Schedule and Materials

Here is your new Unit 3 Schedule and two sheets

http://h1.ripway.com/DrCherdack/HonUnit3-1DMomSched10-11.doc


http://h1.ripway.com/DrCherdack/Unit5ProblemSheet.doc


http://h1.ripway.com/DrCherdack/Unit5extraproblemsr1.doc

AP Ferryman Lab

There is a fair amount of confusion about this lab so let me try to sort it out here.

We did most of the activities in class. First we had o river current. The boat crossed the river going 100.8 m in 5.04 s indicating that its velocity with respect to the water [ v b,w] was 20 m/s and in this case due north. The with the boat point straight north , i.e. heading = 0 deg, we set the current to 10 m/s. The simulation gave the x displacement as 50.4 m and the y as 100.8. The time again was 5.04 seconds. From this we calculated the total distance traveled and the speed wiht respect to the shore by dividing this distance by the time. We then calculated the velocity using velocity components of vx = 10 m/s and vy = 20 m/s.

We the tried to steer the boat so it would go straight across the river. This required that the component of vb,w in the x direction be -10 m/s . Since we knew vb,w had a magnitude of 20 m/s we could find the direction. Since the simulation reads direction as angle from north ( i.e. theta y) we could find theta x using inv cos (x component/20)and then its complement which would be theta y.

You should be able to include all this in your report and then do the additional work called for. This is all due Monday and is informal.

A purpose and conclusion are required. Did we prove or demonstrate anything ( components, relative velocity, etc.?)

Science and Engineering Fair

Here is a site about a science exhibition and and festival at the end of October.

http://www.njsciencefestival.org

AP Section 5

Several people wrote on the tests despite clear written and oral instructions to not do so. I hate to resort to such silly measures, but next time I will deduct points for tests that have been written on. Checking tests for writing is not a productive use of time and I hope you can show enough maturity in the future to allow us to dispense with this.

AP Unit 3 Schedule

This is the new schedule. It may be revised so stay posted.

http://h1.ripway.com/DrCherdack/APunit3sched%2010-11.doc


http://h1.ripway.com/DrCherdack/Unit_3_Worksheet_1.doc


http://h1.ripway.com/DrCherdack/Unit_3_Worksheet_2r1.doc


http://h1.ripway.com/DrCherdack/Unit_3_Worksheet_3.doc

http://h1.ripway.com/DrCherdack/Unit3problemsheet.doc

http://h1.ripway.com/DrCherdack/unit_3_extraproblemsR2.doc

Honors Assignment

Your assignment for this weekend is two -fold

1) We are beginning to study momentum so read the notes and do the problems at the end. The notes give you all the information you need to answer the problems.

http://h1.ripway.com/DrCherdack/Notes%20on%20MomentumRev2.doc

2) Each student must turn in one hard copy paragraph describing in some detail their chosen topic. Do not pass around one file. Also send me your logo and name in one email per group. These are required.