Egg toss lab

We are studying impulse force.  Impulse is the force an object experiences when there is a change in momentum.  The change in momentum equals the impulse force times the change in time.  What time?  The time elapsed as the object changes momentum.

An easy way to demonstrate this is to toss an egg back and forth between two students.  How do you reduce the impulse force?  Look at the equation in the first paragraph. If a student tosses the egg to another student, the change in momentum is equal to the mass of the egg times the speed at which the other student throws the egg.  The catcher can either catch the egg with his hands fixed or he can swing his hands and arms back as he is catching the egg.

If you catch the egg and it stops very suddenly, it will probably crack.  This is great fun the first time!
If the catcher swings his hands and arms back as he catches the egg the egg usually does not crack.  The difference is much more evident if you catch the egg on a cookie sheet instead of your hands.  You can also use a bedsheet.

The key concept to understand is that the momentum is a constant in each situation so if you want to reduce the impulse force you must increase the time it takes to bring the egg from its initial speed to a stop.

There are several great examples in real life such as crush zones designed into the front of a car's frame and body, airbags in your car, etc.

The opposite is also true.  If you are hitting a baseball, you only have so much strength.  If you want the ball to have more momentum so that it goes further, you have to increase the time the bat is in contact with the ball as you are hitting it.  In many sports such as baseball, golf and basketball, this is called follow through.

Have fun with the lab.

class discipline

It seems as though some of the homeschool students I teach are not accustomed to deadlines and remembering to bring their completed work to class.  They also have a long list of excuses when they have not finished their work such a: the printer broke, they stayed late at sports practice, they were tired, etc.  They also insist on maintaining some practices that are not correct such as not using scientific  notation and forgetting to include units of measurement.

So we came to a mutual agreement.  Offending students would do pushups, just like in basic training for the military for each infraction.  Did not finish a report?  Ten pushups.   Present a problem solution and not express the answer in scientific notation?  Ten pushups.  The parents I have spoken to about this are all supportive.   The point I am trying to make is that when these students are in college, the military, or have a job,  none of these behaviors are acceptable!

The importance of being able to write well and appropriately to a scientific audience

The class has been writing their egg toss lab reports.  It is important that they write well but also write appropriately to a scientific audience.  In all writing it is important to use proper punctuation, grammar, and sentence structure.  It is also important to write succinctly and concisely and not use trite phrases.

I have never been able to write prose and poetry so I will not comment on the differences between what the students may have learned about writing in their literature, composition, and history classes and what I am teaching them about writing.  Hopefully those differences are not too great.

Examples of phrases and words I do not want to see in lab reports:  honestly, actually, grab the …, who would have thought?,  etc.

We also write lab reports in the third person, present tense, active voice, indicative mood.

For example:  The student rolls the ball.