Fan attached to a sled blowing at the sail

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In summary, the fan blows air into a sail on the back of a sled, which causes the sled to move to the right.
  • #1
cragar
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Homework Statement


a fan is attached to a sled blowing air to the right at a sail
the sled is on ice and friction is neglected and the air around the sled is still
except the air moved by the fan.
will the sled move is so to the right or left.


Homework Equations





The Attempt at a Solution


i think the sled will move to the right becuase that's where the air hits the sail .
what do u guys think
 
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  • #2
Sail and fan are inside the sled.
The molecules of a gas inside a closed container, move with high velocity and collide with the container wall, but the container does not move. Why? What is Newton's first law of motion?
 
  • #3
Newtons first law is inertia , k this is what i am thinking as the fan blade whacks
the air molecule it is given an intial momentum and then the air molecule hits the sail and bounces back thus changing direction and having a greater change in mometum
thus moving the sled to the right.
 
  • #4
According to Newton's first law, body will not move unless we apply an external force on the body.
In your problem, no external force is acting on the sled.
 
  • #5
for every action there is an equal but oppostie reaction and when the air molecule hits the sail and bounces back there is an impulse in mometum greater than that of the original mometum of the air molecule. there fore it will move to the right so i ask u
when the fan intially hits the air molecule and when that molecule hits the sail and bounces back are those changes in momentum the same .
 
  • #6
In a railway compartment, if every passenger hits a ball to the front wall of the compartment, will the railway move forward?
 
  • #7
are these ball's suspended in the atmosphere
 
  • #8
No. they may return back to the passenger or some where else. Even they may go out of the compartment.
In your problem, I presume sail is made up of cloth. In that case, when the fan is on, the sail can take a concave shape.
 
  • #9
i still would like u to explain how when the fan hits the molecule and from when it bounces off that their implueses are the same , and in ur case yes neglecting friction
the railroad car would move forward due to the impulse momentum theorem.
 
  • #10
In a frictionless floor, sitting in the back seat of a car and kicking the front seat, the car will not move forward. Because the car and passenger constitute a single system. To move the system, force must be applied from outside the system.
Moving fan and sail together with the wind produced by the fan in the sled is not possible.
 
  • #11
k i knew the answer to this question before i asked it , we talked about this in my physics class and my professor said that the sled would move forward because of the impusle momentum theroem and he said this is a good question for physics instructors too see if they really know what they are doing , in ur case kicking the seat your body is part of the sled and in our case the air is not part fo the sled. so are u telling me that my professor with a ph.d in nuclear physics is wrong .
 
  • #12
A simpler way to picture it.
1, Imagine a compessed air hose pointing backward = the sled will obviously move forward
2, Then imagine the hose has a loop in it so that coming out of the compressor the pipe goes forward but the nozzle still points back = no change, still fowad
3, Now imagine instead of the loop the jet points forward at a sail and the air bounces off and goes backward = exactly the same as 2
 
  • #13
so ur saying the sled will move
 
Last edited:

1. What is the purpose of a fan attached to a sled blowing at the sail?

The purpose of a fan attached to a sled blowing at the sail is to provide additional propulsion for the sled. By using the force of the wind created by the fan, the sled can travel faster and with less effort.

2. How does the fan attached to a sled blowing at the sail work?

The fan creates a forceful stream of air that is directed towards the sail. This air flow creates a pressure differential, with higher pressure behind the sail and lower pressure in front of it. This pressure differential creates a force that propels the sled forward.

3. Can the fan attached to a sled blowing at the sail be used in any type of weather?

The effectiveness of the fan attached to a sled blowing at the sail depends on the wind speed and direction. In order for the fan to be effective, there needs to be a consistent and strong enough wind to create the necessary pressure differential. Therefore, the fan may not be as effective in calm weather or if the wind is coming from the wrong direction.

4. Is the fan attached to a sled blowing at the sail safe?

As with any activity, safety precautions should be taken when using a fan attached to a sled blowing at the sail. It is important to make sure that the fan is securely attached to the sled and that the sail is properly set up. Additionally, it is important to use caution and common sense while riding the sled, especially at high speeds.

5. Are there any other benefits to using a fan attached to a sled blowing at the sail?

In addition to providing additional propulsion, using a fan attached to a sled blowing at the sail can also be a fun and unique way to enjoy winter activities. It can also be a great way to teach concepts of physics and aerodynamics to children and students.

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