10-20-10 homework

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course Phy 201

Acceleration vs. Ramp SlopeUsing the TIMER program, time a ball down the steel ramp when the ramp is supported by a single domino lying flat. Do five trials with this setup.

Report the median time, the distance the ball traveled from rest in this time, and the resulting acceleration.

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Time

1.81

12cm/1.81s=6.62cm/s

12/6.62cm/s=1.81cm.s

2.262

12cm/2.262s=4.58cm/s

2.62cm/s

1.794

12cm/1.794s=6.68cm/s

1.79cm/s

2.059

12cm/1.794s=6.68cm/s

1.79cm/s

1.653

12cm/1.94s=6.18cm/s

1.94cm/s

Median=1.794

Assuming `ds = 12 cm, you have calculated `ds / `dt, which gives you vAve.

You then appear to divide `ds by vAve, which gives you your time interval `dt.

However you have not calculated average acceleration, which is `dv / `dt.

What is `dv? What therefore is the average acceleration?

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Report the rise and run between two points of the ramp and the resulting slope.

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Rise=y=1m

Run=x=12cm

1m/12cm=1m/cm

I believe rise is 1 cm, not 1 m.

1/12 = .083, not 1.

1 cm / (12 cm) = .083.

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Repeat with the domino lying on its long edge, so that the rise is equal to the width of the domino. Do five trials with this setup.

Report the median time, the distance the ball traveled from rest in this time, and the resulting acceleration.

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Time

.998

12cm/.998s=12.02cm/s

.99cm/s

1.077

12cm/1.077s=11.14cm/s

1.077cm/s

.843

12cm/1.077s=11.14cm/s

1.123

12cm/1.123s=10.685cm/s

1.123cm/s

12cm/.936s=12.82cm/s

.936

Median=.998

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Report the rise and run between two points of the ramp and the resulting slope.

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Rise=y=2cm

Run=x=12cm

2cm/12cm=6cmslope

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Based on these two setups, at what rate does the acceleration of the ball appear to change with respect to ramp slope?

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YES

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Now time the toy car down the wood ramp, using two different slopes. Be sure the ramp is straight. Suggestion: Use your textbook to help. Support it at one end with something reasonably rigid, whose thickness you can measure with good accuracy (for example a couple of CD or DVD cases would be a good choice, using one for the first setup, and both for the second). Using one hand hold the wood piece flat against the book, release the car with another hand, and operate the TIMER with your third hand. If you don't have three hands, adapt the suggestions accordingly. You might also find it helpful to use the steel ramp to press the wood ramp against the book.

For the first slope:

Report the median time, the distance the ball traveled from rest in this time, and the resulting acceleration.

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Time

0.624

16cm/.624s=25.82cm/s

0.686

16cm/.686s=23.32cm/s

0.764

16cm/.764s=20.94cm/s

0.811

16cm/.811s=19.728cm/s

0.717

16cm/.717s=22.31cm/s

Median=0.717

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Report the rise and run between two points of the ramp and the resulting slope.

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Rise=y=2cm

Run=x=16cm

Slope 8cm

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For the second slope:

Report the median time, the distance the ball traveled from rest in this time, and the resulting acceleration.

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Time

0.437

16cm/.437s=36.613cm/s

0.437

16cm/.437s=36.613cm/s

0.405

16cm/.405s=39.506cm/s

0.436

16cm/436s=36.69cm/s

0.374

16cm/364s=43.95cm/s

Median=.0437

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Report the rise and run between two points of the ramp and the resulting slope.

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Rise=y=4cm

Run=x=16cm

Slope=4cm

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Based on these two setups, at what rate does the acceleration of the ball appear to change with respect to ramp slope?

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YES

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Is acceleration independent of position and velocity?

You were asked previously to design an experiment to test whether acceleration is independent of position and velocity, on a ramp with constant incline.

Do a 30-minute preliminary run, using the TIMER. Just take whatever data you can in 15 or 20 minutes, and give a brief report of your setup, your data and your results. Try to be as accurate as possible within the 15-20 minute time constraint.

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1cm

With the wood ramp and a steel ball

Timer

0.998

16cm/.998s=16.032cm/s

0.904

16cm/.904s=17.699cm/s

0.936

16cm/.936s=17.094cm/s

0.967

16cm/.967s=16.546cm/s

0.967

16cm/.967s=16.546cm/s

Median=0.967

Rise= 1cm

Run=16cm

Slope=.0625

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&#Good responses. Let me know if you have questions. &#

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You will need to modify your calculation of acceleration for each of these situations.

&#Please see my notes and, unless my notes indicate that revision is optional, submit a copy of this document with revisions and/or questions, and mark your insertions with &&&& (please mark each insertion at the beginning and at the end).

Be sure to include the entire document, including my notes.

If my notes indicate that revision is optional, use your own judgement as to whether a revision will benefit you.

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