What are the fallibility pitfalls when solving problems with the definition of momentum???

It should be how convenient it is. The drag is related to the pressure difference, which happens to be in the momentum equation. The lift force is equivalent to considering only the vertical direction, so the force is decomposed into the vertical direction.

By the way, my teacher taught to use the approximate pressure coefficient to calculate, the horizontal direction is the resistance, and the vertical direction is the lift. That's why I think it's convenient to use whatever formula is convenient.

The law of conservation of momentum, together with the law of conservation of energy and the law of conservation of angular momentum, are the three fundamental conservation laws in modern physics. Initially, they were inferences of Newton's laws, but later it was discovered that they were far more applicable than Newton's laws, and were more fundamental physical laws than Newton's laws, reflecting the nature of space-time.

1. p=p means that the total momentum at the beginning of the interaction of the system is equal to the total momentum at the end of the interaction (or at some intermediate state).

2. δp=0 means that the change in the total momentum of the system is zero. If the system under study consists of two objects, it can be expressed as:

Both sides of the equation are vector sums).

3、δp1=－δp2

That is, if the system is composed of two objects, then the momentum change of the two objects is equal in magnitude and opposite directions, and the vector nature of the momentum change should be noted here.

Momentum, i.e., the product of the mass and velocity of an object, is used to describe the effect of a moving object and is a measure of the mechanical motion of an object.

Momentum p=mv, the unit depends on the unit of mass and the unit of velocity. In the International System of Units, the unit of momentum is kg·m s.

Momentum has three properties: vector, instantaneous, and relative. The direction of momentum is the direction of velocity, whereas velocity in the definition of momentum is instantaneous velocity, therefore, momentum is a state quantity. Since the velocity of the object is related to the selection of the reference frame, the momentum of the object is also related to the selection of the reference frame, usually with the ground as the reference frame.

Law of Conservation of Momentum: If the system of interacting objects is not acted upon by an external force, or if the sum of the external forces is zero, the total momentum of the system remains the same.

Mathematical Expressions:

The total momentum p before the interaction of the system is equal to the total momentum p after the interaction')

2.p=0 (the total momentum increment of the system is zero).

3.p1=- p2 (a system of two interacting objects with equal momentum increments and opposite directions).

m2v2'(The two bodies that interact make up the system, the sum of the pre-momentum is equal to the sum of the post-momentum).

Establishment conditions:1The net force of the system that is not subjected to an external force or the system is subjected to an external force is zero.

2.Although the net force of the external force on the system is not zero, it is much smaller than the internal force of the system, such as the friction force in the collision problem, the gravity force in the process, etc., the external force is much smaller than the internal force of the interaction, and the total momentum of the system can be approximated to be conserved.

3.Although the resultant force of the external force on the system is not zero, but the component in a certain direction is zero, then the component of the total momentum of the system in that direction remains the same.

1.Elastic collision: During the collision, not only the total momentum of the system is conserved, but also the kinetic energy before and after the collision. In general, the collision between two hard balls is very close to an elastic collision.

2.Inelastic collision: The kinetic energy in the collision is not conserved, only the conservation of momentum is satisfied. The collision between two objects is generally an inelastic collision.

3.Completely inelastic collision: two objects that become one after collision and have a common velocity, satisfying the law of conservation of momentum, but with the greatest loss of kinetic energy.

If a system is not subjected to an external force or the vector sum of the external forces is zero, then the total momentum of the system remains the same, and this conclusion is called the law of conservation of momentum. Momentum theorem ft=mv2-mv1

The content of the law of conservation of momentum: the total momentum of a relatively acting object remains unchanged if the system is not acted upon by external forces or the sum of the external forces is zero.

Expression: p1+p2=p1 +p2 or: m1v1+m2v2=m1v1 +m2v2

Average force.

I don't know how to find this average force.

Your formula looks like the momentum theorem.

But this average force is a bit vague, can you describe what the average force is.

When to use ??? It can be used in the case of the impulse theorem in physics.

3. Momentum theorem.

1) Content: The impulse of the resultant force experienced by the object is equal to the change in momentum of the object.

Expression: ft=mv mv=p p, or ft=p momentum theorem formula f is the net force of all external forces, including gravity, experienced by the object of study. It can be a constant force or a variable force.

When the resultant external force is a variable force, f is the average value of the combined external force on the action time. p is the initial momentum of the object, p is the final momentum of the object, and t is the action time of the resultant external force.

2) f t= mv is vector. When applying the momentum theorem, we should follow the parallelogram rule of vector operations, or we can use the orthogonal decomposition method to convert vector operations into scalar operations. Suppose the component of the resultant external force on the x (or y) axis is expressed in terms of fx (or fy).

or) and vx (or vy) denote the components of the initial and final velocities of an object on the x (or y) axis, then.

fx△t=mvx－mvx0

fy△t=mvy－mvy0

The above two equations show that the component of the impulse of the resultant external force on a certain coordinate axis is equal to the component of the increment of the momentum of the object on the same coordinate axis. When writing the component equation of the momentum theorem, for a known quantity, a positive value is taken for those that are in the same direction as the positive direction of the coordinate axis, and a negative value is taken for those that are in the opposite direction of the positive direction of the coordinate axis;For unknown quantities, it is generally assumed that the direction is positive, and if the result is positive. Note If the calculated result is negative, the actual direction is opposite to the positive direction of the coordinate axis.

ft=mv′－mv=p′－p

The people who hate sticking things the most urge to adopt my answers.

ft = mv = i i, i.e. momentum in that direction = impulse in that direction = mass multiplied by velocity in that direction = force in that direction multiplied by action time.

There is no advantage to this, if you can understand it well and be familiar with it, it is the letter with a direction, according to the definition of the column formula, if you can't understand it well or are afraid of making mistakes, the letter is a quantity, and then write the symbol. Either way, you have to make it clear.

Momentum definition: The product of the mass of an object and its velocity. p=mv impulse is the cumulative effect of force on time.

That is, the product of force and time. i=The impulse of the FT force on the object, which causes the momentum of the object to change, and the impulse is equal to the change in the momentum of the object. i= δp, i.e., ft = δmv

Upstairs is not clear. Let me rephrase: ek=(mv 2) 2, p=, so p 2=2mek. The formula is obtained after the prescription.