# Conservation of Momentum Question.

• skg94
In summary: In fact, it's a bit more complicated than that. The vector after the collision is not simply the vector before the collision multiplied by (v_before*20), but has a component in the opposite direction (v_after*-20).
skg94

## Homework Statement

An 800 kg airplane traveling at a velocity of 120 m/s [30o N of E @ 20o above the horizon] collides with a stationary 1200 kg helicopter. If the velocity of the airplane after the collision is 65 m/s [40o N of E @ 60o above the horizon] what is the final velocity of the helicopter?

## The Attempt at a Solution

I don't understand what to do with the 20 degrees above the horizon part in both the parts.

skg94 said:

## Homework Statement

An 800 kg airplane traveling at a velocity of 120 m/s [30o N of E @ 20o above the horizon] collides with a stationary 1200 kg helicopter. If the velocity of the airplane after the collision is 65 m/s [40o N of E @ 60o above the horizon] what is the final velocity of the helicopter?

## The Attempt at a Solution

I don't understand what to do with the 20 degrees above the horizon part in both the parts.
First, choose a coordinate system.

The 20° angle should allow you to find a vertical and a horizontal component of the velocity of the airplane. Then break the horizontal component into an eastward component and a northward component.

...

The way I read it, that is the plane's attitude. That is, it is not in level flight, but has a 20 degree angle up before the collision. The collision appears to take place in two dimensions, [STRIKE]in a vertical plane.[/STRIKE]

Last edited:
Isnt, 20 degree above the horizon same as 20 degree N of E? 20 degrees from 0 right

Nope. Angles east or west of north are in a horizontal plane. Angles above or below the horizon (itself essentially a horizontal plane) are in a vertical plane.

tms said:
The way I read it, that is the plane's attitude. That is, it is not in level flight, but has a 20 degree angle up before the collision. The collision appears to take place in two dimensions, in a vertical plane.
The plane of the collision may be found from the airplane's velocity vector before the collision and it's velocity vector after the collision. This plane is not vertical.

SammyS said:
The plane of the collision may be found from the airplane's velocity vector before the collision and it's velocity vector after the collision. This plane is not vertical.

You're right, of course, and neither is it horizontal.

## 1. What is the law of conservation of momentum?

The law of conservation of momentum states that the total momentum of a closed system remains constant. This means that in the absence of external forces, the total momentum before an interaction is equal to the total momentum after the interaction.

## 2. How is momentum defined?

Momentum is defined as the product of an object's mass and velocity. It is a vector quantity, which means it has both magnitude and direction.

## 3. Why is conservation of momentum important?

Conservation of momentum is important because it is a fundamental law of nature. It helps us understand and predict the motion of objects in a variety of situations, from collisions to explosions. It also plays a crucial role in the fields of physics, engineering, and astronomy.

## 4. Does conservation of momentum apply to all types of interactions?

Yes, conservation of momentum applies to all types of interactions in a closed system. This includes collisions, explosions, and even interactions involving multiple objects.

## 5. Can momentum be transferred between objects?

Yes, momentum can be transferred between objects. This is known as an impulse, which is the change in momentum of an object due to a force acting on it for a certain amount of time. The total momentum of the system remains constant, but within the system, momentum can be transferred from one object to another.

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