Several questions on an experiment on electrostatics

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Discussion Overview

This discussion revolves around an experiment involving electrostatics, specifically the interaction between a charged rubber balloon and a neutral aluminum can. Participants explore questions related to the mechanics of rolling objects, the significance of induced charge, and the nature of electric charge resulting from rubbing materials.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested
  • Homework-related

Main Points Raised

  • One participant questions whether the mass of an object affects its ability to roll, suggesting that heavier objects may not roll easily.
  • Another participant asks if the rubbing effect on the balloon remains significant when it is moved away from the can.
  • There is a discussion about the nature of the aluminum can being neutral and the balloon being positively charged after rubbing, with one participant seeking clarification on whether this is the intended implication of the experiment.
  • A participant introduces the concept of induced charge, explaining that the balloon attracts electrons in the can, causing the side of the can nearest the balloon to become negatively charged.
  • Questions arise regarding the charge of the balloon, with one participant noting that according to the triboelectric series, rubber should gain electrons, leading to confusion about whether the balloon should be negatively charged instead.
  • Participants express uncertainty about the mechanics of rolling and the conditions that allow an object to roll.

Areas of Agreement / Disagreement

Participants express varying levels of understanding regarding the principles of electrostatics and the mechanics of rolling objects. There is no consensus on the nature of the charges involved or the implications of the experiment, indicating multiple competing views and unresolved questions.

Contextual Notes

Some participants reference concepts such as induced charge and the triboelectric series, but there are limitations in the discussion regarding the assumptions made about charge interactions and the mechanics of rolling. The relationship between mass and rolling ability remains unclear.

Who May Find This Useful

This discussion may be of interest to students exploring basic electrostatics, educators seeking examples of student inquiries, and individuals curious about the principles of charge and motion in physics experiments.

iknownth
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Move a can without touching it
1. Place an empty aluminium can on a table so that it can roll freely.
2. Rub an inflated rubber balloon on your hair.
3. Hold the rubbed balloon several centimetres away from the can and move it away from the can slowly.
4. Put the balloon on the opposite side and see if the trick still works.

My questions:
1) What makes an object roll? It is obvious that a heavy object cannot roll easily, so, can the mass of an object determine whether it can roll or not?
2) Is the rubbing effect in step 2 still significant for steps 3 & 4?
3) "The aluminium can is an neutral object and the rubber balloon is positively charged after rubbing with hair. Thus, it can attract the aluminium can." Is it what the experiment what to imply?

Thanks in advance.
 
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Where did you get these questions? They look an awful lot like basic homework questions. If so, this should be in the "homework" section. Even if not, it won't do you any good for someone else to answer them until after you have thought about it for a while yourself. Do you know anything about "electro-statics"? Do you know what "induced charge" is? What do you think is happening here?
 
...
These are my questions and I have thought about it for some time. I really don't understand. "The aluminium can is an neutral object and the rubber balloon is positively charged after rubbing with hair. Thus, it can attract the aluminium can." This is what I think is happening here. I just know that there is charging by rubbing and an attraction between a neutral object and a charged object.
 
Do you know what "induced charge" is? Yes, rubbing the balloon on your hair transfers some electrons from the balloon to you hair, leaving your hair (temporarily) negatively charged and the balloon positively charged. When you hold the balloon near the neutral can, the balloon attracts electron in the can so that the side of the can nearest the balloon becomes negatively charged (it is important here that electrons can move freely in metals), so that the can itself acts as if it were negatively charged.
 
The balloon becomes positively charged temporarily, then why can steps 3 & 4 of the experiment still be carried out?
How do we know if an object becomes positively charged or negatively charged? By the triboelectric series, rubber should be more likely to gain electrons. Should the balloon be negatively charged? Does the charge matters?
Can you also answer my first question? What makes an object roll?
 

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