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Hi, I have just joined the forum. Thank you all for being a part of such places so that people like me can get answers to the questions on their minds!

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I have been trying to understand how a quadcopter yaws. Referring to the figure below which is bird's eye view of a quadcopter:

image credit : link

While the quadcopter is just hovering, the net angular momentum of the system is zero, since the angular momentums of motor set A and motor set B will be equal in magnitude and opposite in direction. So, far, so good.

Now, if I increase the rpm, so the angular velocity(ω) of the propellers, of the motor set B; then they will produce more(in magnitude) angular momentum w.r.t motor set A. So, the total angular momentum of the system will not remain at 0 but will increase towards upward(out of the page) direction. At this point, the phenomenon which causes quad to yaw comes into play, the quadcopter starts to rotate in the opposite direction of motor set B, i.e clockwise, to preserve previous net angular momentum of the system, which was 0. So, at this point, we call it

If I am, then, I get confused when I think the same conservation thing for linear momentum. So, we have our car at rest. So the initial linear momentum of the system is 0 since the speed is 0 (v=0). Then we increase gas pedal, and car starts to move. So the final linear momentum of the car is not 0 anymore. But, why, something similar to the quad case does not happen? In that case, system was counteracting the change in the momentum. But our car just gained momentum.

I know this part sounds very silly, but, I think I have some misunderstandings somewhere. So, any help would be appreciated.

Thanks in advance.

---------------------------

I have been trying to understand how a quadcopter yaws. Referring to the figure below which is bird's eye view of a quadcopter:

image credit : link

While the quadcopter is just hovering, the net angular momentum of the system is zero, since the angular momentums of motor set A and motor set B will be equal in magnitude and opposite in direction. So, far, so good.

Now, if I increase the rpm, so the angular velocity(ω) of the propellers, of the motor set B; then they will produce more(in magnitude) angular momentum w.r.t motor set A. So, the total angular momentum of the system will not remain at 0 but will increase towards upward(out of the page) direction. At this point, the phenomenon which causes quad to yaw comes into play, the quadcopter starts to rotate in the opposite direction of motor set B, i.e clockwise, to preserve previous net angular momentum of the system, which was 0. So, at this point, we call it

*conservation of angular momentum*of the system.**Am I consistent with the laws of physics so far?**If I am, then, I get confused when I think the same conservation thing for linear momentum. So, we have our car at rest. So the initial linear momentum of the system is 0 since the speed is 0 (v=0). Then we increase gas pedal, and car starts to move. So the final linear momentum of the car is not 0 anymore. But, why, something similar to the quad case does not happen? In that case, system was counteracting the change in the momentum. But our car just gained momentum.

I know this part sounds very silly, but, I think I have some misunderstandings somewhere. So, any help would be appreciated.

Thanks in advance.

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