Candle Flame in Upward-Accelerating Lift: Why?

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In summary, when a lift accelerates upwards, the shape of the flame of a candle in it would become taller and thinner due to the air sloshing towards the bottom. This is because the normal air, being more massive, has greater inertia and tends to be denser at the bottom, pushing the balloon upwards even more. Similarly, a helium balloon would also be affected by the air sloshing and would rise to the ceiling of the lift when it accelerates upwards. This is also seen in the example of a helium balloon on a rope in a moving car, where the balloon moves towards the direction of the acceleration. The same concept applies to the flame in the candle, as its shape would also change due to the air slo
  • #1
joker_900
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How would a lift accelerating upwards affect the shape of the flame of a candle in it? My instinct says it would flatten it, but I'm not sure how to explain why. Any help?
 
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  • #2
Consider that the flame is lighter than air. How would a helium balloon react under the same circumstances?
 
  • #3
Danger said:
Consider that the flame is lighter than air. How would a helium balloon react under the same circumstances?

Hmm well in a normal situation the balloon rises because the upthrust (due to pressure difference) is greater than its weight and so pushes it to a less dense region. So when the lift accelerates upwards, i guess the normal air, being more massive, has greater inertia so tends to be denser at the bottom? Therefore pushing the balloon upwards even more?

So would the flame get taller then?
 
  • #4
In my opinion (if air does not extinguish the candle)the flame of the candle MIGHT get flattened but it will ignite more than at constant velocity or at rest, because of inertia.The flame would tend to move downwards because of inertia which means more of the chemical substance of the candle would get melted so more fuel for ignition.
 
  • #5
Supposing the elevator is closed box,the pressure of air will change (if the elevator is accelerating).
Under these circumstances it is sufficient to consider the change in candle flame just as caused by change of an atmospheric pressure.
 
  • #6
Danger said:
Consider that the flame is lighter than air. How would a helium balloon react under the same circumstances?

Indeed, that's a very good hint.

Another classic is this : consider a Helium balloon on a rope. As you are sitting in a car, you hold the rope (to be clear : the balloon rises and finds a position at the ceiling of the car :)) and the car accelerates foreward. What will happen to the balloon ? Does it remain fixed in its position, does it move foreward (same direction as the acceleration), does it move backward etc etc ?

marlon
 
  • #7
Hmmm
What happens to the flame in the candle then??

Does it flatten, being the explanation that its inertia wants to keep it from accelerating?
How does it relate to the balloon scenario?
 
  • #8
In my personal sense,if the lift is airproof,the flame will not easily been seem to flat.if you found it flat,it doesnot matter with accelerate,it does matter with the v of air
 
  • #9
I like Danger's hint too.

The best visualization I've heard is to imagine the air as a fluid that 'sloshes around'. As the lift accelerates upwards, the air sloshes to the bottom, making the flame taller and thinner. As the lift accelerates downwards, the air sloshes to the top, making the flame shorter and flatter.
 

FAQ: Candle Flame in Upward-Accelerating Lift: Why?

1. Why does a candle flame point upward in an accelerating lift?

The upward direction of the candle flame is due to the force of buoyancy. As the lift accelerates upward, the surrounding air becomes less dense and the warmer air produced by the candle rises, creating a difference in air pressure that causes the flame to point upward.

2. What is the role of gravity in the behavior of a candle flame in an accelerating lift?

Gravity plays a minor role in the behavior of a candle flame in an accelerating lift. While it does exert a force on the flame, it is offset by the upward force of buoyancy. Therefore, gravity does not significantly affect the direction of the flame.

3. Does the height of the lift affect the behavior of the candle flame?

The height of the lift does not significantly affect the behavior of the candle flame. As long as the lift is accelerating upward, the surrounding air will become less dense and the flame will continue to point upward.

4. How does the shape of the candle flame change in an accelerating lift?

In an accelerating lift, the shape of the candle flame will elongate and become more pointed in the upward direction. This is due to the change in air pressure and the upward flow of warm air.

5. Can the behavior of a candle flame in an upward-accelerating lift be replicated in any other conditions?

Yes, the behavior of a candle flame in an upward-accelerating lift can also be observed in other situations where there is a difference in air pressure, such as in a hot air balloon or on a windy day. As long as there is a difference in air density and the upward flow of warm air, the flame will point upward.

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