June 11, 2007

The Physics Corner

with Professor A. Joseph Rivers, Ph.Don't

A brief tutorial, with a case study to follow.


In a collision between two objects, both objects experience forces which are equal in magnitude and opposite in direction. Such for
ces cause one object to gain momentum and the other object to lose momentum. According to Newton's third law, the forces on the two objects are equal in magnitude. While the forces are equal in magnitude and opposite in direction, the acceleration of the objects are not necessarily equal in magnitude. In accord with Newton's second law of motion, the acceleration of an object is dependent upon both force and mass. Thus, if the colliding objects have unequal mass, they will have unequal accelerations as a result of the contact force which results during the collision.

The Law of Momentum Conservation in Real World Applications

Lets observe the physics of collision between objects of unequal mass. Two objects are needed for this experiment. First, a Toyota Hiace with a height of 1980mm (1.98m, 6.496063ft). See figure 1a below.

Figure 1a
Second, a fire sprinkler; i.e., the part of a fire sprinkler system that discharges water when the effects of a fire have been detected, such as when a predetermined temperature has been reached. See illustration v8 following. This object has far less mass than the Hiace and is an excellent object to demonstrate the unequal acceleration as a result of the contact force which results during a collision.

Illustration v8.

The venue for this study should be a vehicular parking structure composed of several floors with a posted ceiling height not to exceed 2m (6.5616798ft), as this will accommodate the height of the Toyota Hiace, allowing a clearance of 20mm (0.78740157in) . To ensure proper results, the vehicular parking structure must also have an area with a ceiling height below the posted 2m (6.5616798ft) height, with no signage indicating that this particular area is in fact shorter than the rest of the area. See diagram 867.5309 following.

Diagram 867.5309.

You are now ready to proceed with the experiment. To ensure results which are verifiable, it is advisable to have 4 other participants inside the Hiace to accompany you. Also, make sure to attempt this experiment with this safety precaution in mind: conduct the experiment while leaving the vehicular parking structure as opposed to entering; this will help you avoid unwanted interference and variables intruding from the outside environment.

Park the Hiace so that the rear is approximately 6m (19.685039ft) from the sprinkler head. Place the vehicle in reverse, accelerating toward the sprinkler head. Reach approx. 5km/h (3.1069444mph) and continue until sounds of metal crunching together indicate that you have made contact with the sprinkler head. When you hear the sound, stop Hiace, then pull forward. Observe how the object with larger mass (Hiace) completely destroys the object with smaller mass (sprinkler). Exit vehicle for further inspection, ignoring the laughter coming from the other participants. Be careful when observing: large volumes of water will exit the overhead pipe. Do not attempt to measure the volume of the water as it is certainly unmeasurable. To complete this experiment, quickly exit the parking structure, informing the parking attendant on the bottom floor that there is a situation which needs immediate attention on level P3. This last step is crucial, as it will assuage any guilt incurred upon the one conducting said experiment.


SouthAsiaRocks said...

Wow! So informative... I learned so much in that blog :)

Mama D said...

Reminds me of a certain "scooter" incident.Thanks for the healing laughter!
I'm going to have to hear the story LIVE and in the first person.
Oh, by the way, do you need the number of a good anti-deportation lawyer?
Save some adventures for our next visit!

C-Love said...

Absolutely hilarious, thanks for the laugh.

jdk0103 said...

hahahaha, definitely had to be there! Let's just say we were quite amused :) Thankfully it wasn't the Unser!

Cara said...

The second time being exposed to the story, although still funny, tugged at the "science nerd" part of my heart...I too have had some interesting laboratory experiments go awry...

Anonymous said...

HI-LARIOUS!! Wish I could have heard it from Sharon, I would have laughed harder and possibly to the point of tears! Hope you had a great anniversary! Miss ya tons! <3 Lauren

KelleT said...

Rich! You're gonna be in trouble when your boss gets home!

Chanclers said...


sunnybeachgirl said...

Mrs. Sosa here... let me tell ya, I'm sure glad you're not in an Asian prison or somethi'n for all the trouble you're causing! I could see it now, two tall white kids among a crowd of big pink and orange get-ups eating fish heads and rice in a nice humid jail cell... whee-yoo good thing that didn't happen!

I haven't read your blog for a while (I know shame on me!), but it was nice catching up... you two are certainly on the go... especially on the go-cart ring. Too bad those drive'n skills don't translate to driving a Toyota Hiace! =]

Anthony and Sharon said...

Mama- He had much more control than during the scooter incident.

Justin&Daniela- Thanks for laughing along with us...the Hee-atch is a MUCH better candidate for an experiment like this than our precious Unser!

Cara- It seems like I remember something about smoke and UNF and people exiting the building...

Lauren- Keep commenting! And yes, when I tell it it's way more dramatic

Chanclers- Yes we are.

Mrs.Sosa- Yes you do need to visit the blog more:)

Miranda M. said...

Oh...You, you and your ways!
Too funny.
Love you,

Jennifer B said...


Jennifer B said...

Oh, I get it now. duh! I just read it again!

Jennifer B said...

I wanted to make another comment because I just noticed the wheelchair beside the word verification box and thought it might be fun to try it that way.

C-Love said...

What's going on guys? It's been almost two weeks. I always love your blog and this break is getting a little long.

I need to read about your exciting life to feel better about my own, less-than-exciting existence.