How does mass influence energy transfer?

[elderj]

Summary:: How does mass influence energy transfer?

Can someone help me with this question?
Thanks!

 

[berkeman]

Summary:: How does mass influence energy transfer?

Can someone help me with this question?
Thanks!

Welcome to the PF.

There are obvious answers, like a light plastic cup dropped on a tile floor usually will not break, while a wine glass will. But I'm sure you know that. And a bowling ball dropped on the tile floor will transfer a lot more energy in the collision with the floor compared to a light ball.

But you probably have some other question in mind. Could you please try to say more? Also, it looks like you might work in the education field (using my Mentor superpowers) -- are you a teacher working on a lesson?

 

[phinds]

Can someone help me with this question?

No. It's too vague. Be much more specific for a scenario you are asking about.

EDIT: I see Berkeman has faster fingers than I do.

 

[berkeman]

No. It's too vague. Be much more specific for a scenario you are asking about.

Okay, okay, you're so strict! I should have asked which grade levels she teaches. There, you happy now?!

 

[FactChecker]

For instance, are you asking about a collision of moving objects? Or about the heat transfer between stationary objects in contact? Or about some other scenario?

 

[elderj]

Hi everyone and thank you for your time!
I am a high school teacher who just conducted a stair climbing physics lab in our energy unit.

Students compared their work generated walking vs running. They did this for power as well. They saw a difference in walking vs running in terms of POWER generated.

A thought question was suggested in our curriculum guide for me 2 ask. That question is does mass influence energy transfer in this stair walking lab?

 

[FactChecker]

Energy is the potential to do work. Work is force times distance. Both are measured in the same units (jouls). Work can be considered as the transfer of energy.
So a heavier person climbing stairs for the same distance is doing more work. His increase in work is proportional to his increased weight. The speed (walk versus run) does not matter.

 

[phinds]

What energy transferred to what?

For example, a very heavy out-of-shape person is going to generate more heat climbing stairs than a skinny person but I have NO idea what you have in mind. Please be more specific in your question.

DAMMIT ! Beat to the punch again. Guess I'm slowing down in my old age

 

[FactChecker]

What energy transferred to what?

A good question, especially for this stair climbing example. The chemical(?) energy of the muscles is just being changed into the potential energy of the body going higher on the stairs. So there is no energy transfer out of the person.

 

[phinds]

A good question, especially for this stair climbing example. The chemical(?) energy of the muscles is just being changed into the potential energy of the body going higher on the stairs. So there is no energy transfer out of the person.

Well, there WILL be some loss of radiated heat.

 

[FactChecker]

Well, there WILL be some loss of radiated heat.

Good point.

 

[hmmm27]

A thought question was suggested in our curriculum guide for me 2 to ask. That question is does mass influence energy transfer in this stair walking lab?

During the exercise - assumedly a student climbing up stairs - in what form is the energy at the beginning, and what form at the end.

 

[kuruman]

I agree with @FactChecker that some portion of biochemical energy is converted into mechanical (potential) energy. That's not all. Another portion of the biochemical energy spent by the student is converted to kinetic energy of the student. Of course this does not count as energy transfer out of the system, in this case the student, as @FactChecker already indicated.

But wait $\dots$ there is more! Momentum conservation requires that the stairs and the Earth recoil as the student climbs the stairs which means that yet another part of biochemical energy is transferred to the Earth as kinetic energy of the recoil. Admittedly this kinetic energy is much much smaller than the kinetic energy of the student, by a factor $\frac{m_{student}}{M_{Earth}}$. It may be negligible but it is not zero. In fact, I think this is a prime example illustrating "how mass influences energy transfer." If the student were to push against an object less massive than the Earth, say walk on a platform on wheels, the energy transfer to the platform would be much more noticeable.

 

[elderj]

Thank you everyone for helping me. This has helped a lot!