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# Physics/Post impact physics

Question
A solid object hits an impenetrable and unbreakable glass windshield and the object is not deformed but only bounces off in the opposite direction with reduced kinetic energy. Some of the object's kinetic energy was transformed into heat and some into sound. Can one calculate the intensity of the sound generated if one knows the initial kinetic energy of the object but does not know the heat energy produced in the collision?

In order to bounce in this way, any reasonable object would have to be deformed in some way.  However, I'll go with your assumptions.  There is not way to calculate the heat and sound, because your question (as posed) provides no physical parameters for measuring either.  The conditions are weird, all-around, as you must conserve both momentum and energy.  Therefore, change in momentum must either go into the unbreakable windshield and into the sound waves (since heat energy generally carries little to no momentum, even in a heat flow).  That's an awful lot of momentum, even for a small object, to carry away with just sound.  But there are no physical conditions here or parameters given that will tell you how the heat and sound are divided up.  You don't know what's heating up, or how much.  All you know is that the change in kinetic energy of the object is somehow split between sound, heat in the object, and heat in the glass.  That doesn't give you enough to answer the question.

Physics

Volunteer

#### Dr. Stephen O. Nelson

##### Expertise

I can answer most basic physics questions, physics questions about science fiction and everyday observations of physics, etc. I'm also usually good for science fair advice (I'm the regional science fair director). I do not answer homework problems. I will occasionally point out where a homework solution went wrong, though. I'm usually good at explaining odd observations that seem counterintuitive, energy science, nuclear physics, nuclear astrophysics, and alternative theories of physics are my specialties.

##### Experience

I was a physics professor at the University of Texas of the Permian Basin, research in nuclear technology and nuclear astrophysics. My travelling science show saw over 20,000 students of all ages. I taught physics, nuclear chemistry, radiation safety, vacuum technology, and answer tons of questions as I tour schools encouraging students to consider careers in science. I moved on to a non-academic job with more research just recently.

Education/Credentials
Ph. D. from Duke University in physics, research in nuclear astrophysics reactions, gamma-ray astronomy technology, and advanced nuclear reactors.