Physics Newton s Laws of Motion, Newton s Laws of Motion

Since the impulse is equal to the change in momentum and the initial velocity is 0, the initial momentum is 0. So ft=mv

v=ft m=1500*meter seconds.

So mv 2 2 = mgh

h=v2 2g=4 2 (2*m.)

So I can jump up the meter.

In the interior, the acceleration of the person is a=(1500-750) 75=10m s*s, the velocity reached in the interior is at=v=10*, the rising height is s1=1 2*at*t=, and then the acceleration is -g, s2=v*v 2g=, so s=s1+s2=, so the height of the bar is s+h=

Momentum theorem. f*t=mv

The athlete gains a speed of 4 meters per second.

again by kinematic formulas.

2 at the end of v - 2 at the beginning of v = 2*gs

So, move the meter upwards.

The impulse gained by the athlete is.

f＊t＝mv＝1500＊0．2＝300n＊sv＝4m／s

Therefore, the maximum kinetic energy it acquires is.

1 2mv 1 2 75 16 600j These kinetic energies are all converted into potential energy.

mgh＝600

Solved h 600 75 10 0 8m

That is, the athlete jumped at a height of 0 8 meters

Newton's laws of motion are as follows:

1. Included contents:

1. Newton's first law of motion.

In the absence of external force, the isolated particle remains stationary or moves in a uniform linear motion.

2. Newton's second law of motion.

Momentum, under the action of an external force, the rate of change of momentum with time is proportional to the external force experienced by the particle and is the same as the direction of the external force.

3. Newton's third law of motion.

The action and reaction forces between the two interacting particles are always equal in magnitude and opposite in direction, and the action is violently closed in the same straight line.

II. Overview. The scope of application of the particle model is that when compared with the distance involved in the analysis, the size of the object appears to be very small, or only the external force of the object is considered, and the internal structure, deformation, rotation, temperature, etc. of the object itself are not important for the analysis. The original version of Newton's laws of motion was only suitable for describing the dynamics of particles, and was not functional enough to describe the motion of rigid and deformable bodies.

In 1750, on the basis of Newton's laws, Euler derived Euler's laws of motion that can be applied to rigid bodies. Later, this law was applied to deformable bodies that were assumed to be a continuum medium. If a group of discrete particles are used to split the representative object, each of which obeys Newton's laws, Euler's laws of motion can be deduced from Newton's laws kernel.

Newton's laws of motion are only established in inertial frames of reference, also known as Newtonian frames of reference.

Newton's laws of motion include Newton's first law of motion, Newton's second law of motion, and Newton's third law of motion, where:

The first law explains the meaning of force: force is the cause of changing the state of motion of an object.

The second law states the effect of force: force causes an object to gain acceleration.

The third law reveals the nature of force: force is an interaction between objects.

The laws in Newton's laws of motion are independent of each other, and their internal logic is self-consistent. Its scope of application is the range of classical mechanics, and the applicable conditions are particles, inertial reference frames, and macroscopic and low-speed motion problems. Newton's laws of motion explain the complete system of Newtonian mechanics and the basic laws of motion in classical mechanics, which are widely used in various fields.

Newton's Three Laws Formula:

Newton's first law states: All objects always remain at rest or in a uniform linear motion under any circumstances when they are not acted upon by external forces.

Newton's second law: The acceleration of an object is directly proportional to the resultant external force on the object, inversely proportional to the mass of the object, and the direction of acceleration is the same as the direction of the resultant external force. Formula: f = ma.

Newton's third law states: The force of action and reaction between two objects, on the same straight line, is equal in magnitude and opposite in direction. Expression: f1 = f2, f1 represents the force, and f2 shows the reaction force.

The law of gravitation is that any two objects in nature are attracted to each other, and the magnitude of gravity is proportional to the product of the masses of the two objects and inversely proportional to the square of the distance between the two objects. It is expressed by the formula as:

f=g*m1m2 (r*r)Silver chain (g= can be read as f equal to g multiplied by m1m2 divided by r.

f: gravitational force between two objects, g: gravitational constant, m1: mass of object 1, m2: mass of object 2, r: distance between two objects.

Chapter 4 Newton's Laws of Motion.

Section 1 Newton's First LawThe Charm of Ideal Segment ExperimentsNewtonian PhysicsThe Cornerstone of Newtonian PhysicsThe Law of InertiaNewton's First Law (Law of Inertia).

Definition: All objects always remain in a state of constant linear motion or at rest, unless a force acting on it forces it to change to this state. Definition of inertia:

The property of an object that maintains a state of uniform linear motion or a state of rest. Inertia vs. Mass: The physical quantity that describes the inertia of an object is their mass. Mass is a scalar quantity, only size, and there is no trembling direction.

Mass unit: kilogram (kg).

Section 2 Experiment: **Relationship between acceleration and force and massThe relationship between acceleration and force The basic idea: keep the mass of the object constant, measure the acceleration of the object under the action of different forces, and analyze the relationship between the speed and force of the tremor.

The basic idea of the relationship between acceleration and mass: keep the force on the object the same, measure the acceleration of objects of different masses under the action of the force, and analyze the relationship between acceleration and mass. Two questions in the development of the experimental protocol: how to draw conclusions from the experimental results af, a1 m

Section 3 Newton's Second Law Newton's second law defines that the magnitude of the acceleration of an object is proportional to the force and inversely proportional to the mass of the object, and the direction of acceleration is the same as the direction of the force. Formula:

f=kma k is the coefficient of proportion, and f refers to the net force experienced by the object. The unit of force is Newton's second law'Physical expression: f=ma unit of force:

Kilogram-meters per square second.

Section 4 Basic Quantities of the Mechanical Unit System: Selected physical quantities that can be used to derive other physical quantities from the relationship between physical quantities. Base Unit:

Units of basic quantities. Derived Units: Units of other physical quantities derived from fundamental quantities based on physical relationships.

System of Units: Consists of base units and derived units. International System of Units (SI):

In 1960, the 11th International Conference on Weights and Measures established an internationally accepted system of units in all fields of measurement.

Section 5 Newton's Third Law Definition of Force and Reaction Force: This pair of forces that interact with each other. Action and reaction forces are always interdependent and coexist.

Newton's third law defines that the force and reaction between two objects are always equal in magnitude and opposite in direction, acting on the same straight line.

Section 6 Solving Problems with Newton's Laws of Motion (1) Determining Motion from Force SituationDetermining Force from Motion Section 7 Solving Problems with Newton's Laws of Motion (2) Equilibrium Conditions of Co-point ForceEquilibrium state: the state in which an object remains at rest or in a uniform linear motion under the action of force. The equilibrium condition of the object under the action of a common point force is that the net force is 0.

Overweight and weightlessness Definition: A phenomenon in which the pressure of an object on a support (or the pull on a suspended object) is greater than the gravitational force on the object. Direction of acceleration:

Vertically up. Definition of weightlessness: A phenomenon in which the pressure of an object on a support (or the pull force on a suspended object) is less than the gravitational force on which the object is subjected.

Acceleration direction: vertically downward. From the kinetic point of view, when the object is moving in free fall, it starts to fall from rest, that is, the initial velocity of motion is 0.

It is only affected by gravity during movement.

In his famous work Principia Mathematica of Natural Philosophy, published in 1687, Newton proposed three laws as the basis for dynamics. These three laws are collectively called Newton's laws of motion, and the mechanical theory established on the basis of Newton's laws of motion is called Newtonian mechanics.

The Chinese translation of Newton's three laws is:

The first law: any object remains at rest or moves in a straight line at a uniform speed, unless a force acting on it forces it to change this state.

The second law: The change in motion is proportional to the applied dynamic force and occurs in the direction of the straight line along which the force is directed.

The third law: for every action, there is always an equal reaction to which it is opposed; In other words, the interaction between two objects towards each other is always equal and pointing in opposite directions.

The velocity is the same before separation (because there is always contact).

So when the acceleration of the ball is equal to the acceleration of the plate.

Just to separate.

At this point, the plank has no support force on the object.

Let the spring elongate at this time

then mg-kl=ma

Get l = (g-a)m k

And l is equal to the descending distance of the plank.

So l=1 2at2

t= (2m(g-a) ka).

Select C to set the rope tension to be F1, the support force between B and A to be F2, and the gravity of the small block to GThey are separated horizontally by F1x and F2X, and vertically by F1Y and F2Y. When moving in smooth segments, they are all at a constant velocity, there is f1x = f2x, f1y+ f2y = g when they just run to the rough section of the track.

If the block does not slide upwards, there is f1y + f2y = g, and the horizontal b has an acceleration to the left.

It can be seen that f1x is less than f2x. If F1 remains unchanged or increases, then F1X and F1Y also remain unchanged or increase, since F1X is less than F2X, we can see that F2X must increase, and then F2 increases, and F2Y also increases, and F1Y+ F2Y is greater than G. The object may have an upward acceleration, contradicting the assumption that the object does not slide.

So f1 must be reduced. f1y is also reduced. According to f1y+ f2y=g, f2y must increase, and then f2 increases.

The magnitude of the reaction force received by the large block in the vertical direction of the small block is also f2y, and the increase of f2y will also increase the pressure between a and the ground.

If the ground is rough enough for B to slide upwards relative to A, then it is easier to understand. The tension of the rope is gone, and the object has an instantaneous upward acceleration, which must be f2y greater than g. And it turns out that there is f1y+ f2y = g, and obviously f2 is increased.

c, because the two objects still have a tendency to move to the left due to inertia b when they first enter the rough section, it is conceivable that the rope will no longer be.

Tight, B moves upwards relative to A, and there is an upward acceleration, so the support force of the ground for A increases.