Verify Newton s Second Law Experiment, Newton s First Law Experimental Method

The same is true for the air cushion rail, which can be used to increase or decrease the weight, and can also use a spring force tester, so that the force can be intuitively expressed, and it is best to be consistent with the direction of the trolley's movement, otherwise there will be an angle. I hope mine can help you, the phone called, it's not easy, hopefully.

M refers to the mass of the trolley. In the experiment, the pulling force f is pulled by pulling the weight disc with a rope and pulling the trolley through the fixed pulley, that is, the total gravity of the weight disc and the weight is the tensile force f, so the pulling force can be changed by adding or subtracting the weights in the weight disc. If you get the paper tape, you can measure the acceleration a. with the formula in the textbook

I would advise you not to bother with this - because no one can experimentally verify Newton's second law - in fact, Newton's second law does not exist at all in terms of quantity on the supporting plane!

Objective] To study the relationship between the acceleration of the trolley and the tensile force when the mass is constant. When the force is constant, the relationship between acceleration and the mass of the car. That is, to verify Newton's second law.

Experimental Principle] The object of the study is the car shown in the figure. The front end of the trolley is tied with a thin rope, the thin rope crosses the fixed pulley, and a small bucket is hung below, and the barrel is filled with sand. Knowing the total mass of the sand and kegs, it is possible to calculate their total weight.

When the total mass of the trolley and the weights on the trolley is much greater than the total mass of the sand and the bucket, the total weight of the bucket can be approximated as the pulling force of the rope on the trolley. Under the tension of the rope, when the trolley moves on the long wooden board, the movement of the trolley is recorded with a dot timer, and the acceleration is obtained, and the relationship between the acceleration of the trolley and the force is studied, so as to maximize the relationship between the acceleration and the mass of the trolley (including the mass of the code removal on the car).

Experimental equipment] EDM timer or electromagnetic dot timer, long wooden board with pulley attached to one end, trolley, paper tape, string, weight, sand bucket, sand, wire, power supply, scale, balance.

Experimental Procedure] 1With the same mass, the relationship between acceleration and force is studied.

l) balance the friction between the trolley and the long plank, in the long plank without fixed pulley, a wooden board is paddled under the end, so that the long plank becomes an inclined plane, and the position of the pad is repeatedly moved so that the trolley sits on the inclined plane and moves in a straight line at a uniform speed.

2) Use a balance to measure the mass m of the trolley, the mass of the keg and the sand m'and record it. Put enamel yards, kegs on the trolley.

Put an appropriate amount of sand into it, so that the total mass of the bucket and sand is much smaller than the total mass of the trolley and weights, and put the mass m and m of the removal code and sand'Record it.

3) Tie the string to the trolley and hang the keg around the pulley. Turn on the power, let go of the trolley and let the trolley drag the paper tape to move, and the dot timer will put a column of dots on the paper tape. Remove the tape and mark the tape number.

Keep the mass of the trolley unchanged, change the quality of the sand, that is, change the pulling force on the trolley, and do a few more experiments. In the experiment, it is necessary to make the mass of the sand and kegs much smaller than the mass of the trolley and weights.

4) Select a more ideal part on each paper tape, mark the counting point, measure the distance between the counting points, and find the value of the acceleration of each paper tape.

5) Fill in the data from each experiment in the table. The magnitude of the force f is equal to the total weight of the sand and the keg (m'+m'g is represented by the ordinate of acceleration a, abscissa is represented by force f, and the corresponding points are drawn on the coordinate plane according to the experimental data. If, within the experimental error range, these points are in a straight line through the origin, it proves that the acceleration is proportional to the applied force.

The weight disc is used to pull the slider to move, and the gravity of the weight disc and the weight in it produces a pulling force, and the total mass of the weight disc and the weight and the slider is the research object m.

Reducing the number of weights to change the amount of tension and placing the reduced weights on the slider ensures that the total mass remains the same.

The experimental method of Newton's first law is the method of experimental reasoning.

1. How Newton's first law was derived.

Newton's first theorem is based on the use of reasoning, which is a scientific research method that ignores secondary factors on the basis of experiments, makes reasonable reasoning, draws scientific conclusions, and achieves the purpose of understanding the essence of the underlying matter. For example, Newton observed the trolley sliding down the inclined plane at the same height, and found that when the resistance is smaller, the speed of the trolley decreases slower, and it is deduced that if the drag is zero, the speed of the trolley will not decrease, and it will move in a straight line at a uniform speed, from which Newton's first law is derived.

2. How to experimentally verify Newton's first law?

Newton's first law is derived by analyzing facts, generalizing further, and reasoning. Although it is impossible to directly verify this quiet law by experiment, all the inferences drawn from the law have withstood the test of practice, so Newton's first law has become one of the recognized fundamental laws of mechanics. Force is responsible for the acceleration of an object.

In other words: force is the cause of changing the state of motion of an object. ）

A basic introduction to Newton's first law:

Newton's first law states that all objects always remain at rest or in a uniform linear motion when they are not subjected to force. In other words, if the resultant force exerted on the object is zero, the velocity of the object is constant. According to this law, a resting object remains at rest unless a resultant force is applied to it.

An object in motion does not change its velocity unless an external force is applied to the object. Note that velocity is a vector quantity, and that all objects always remain at rest or in a straight line at a uniform velocity until an external force forces them to change this state.

On the basis of the research of Galileo and other scientists, the famous British physicist Newton conducted an in-depth study of a large number of experimental facts and summed up a law: when all objects are not affected by external forces, they always remain in a state of rest or a state of uniform linear motion, which is later called Newton's first law, also known as the law of inertia.

In high school textbooks, it is described that all objects always remain at rest or in a state of uniform linear motion, unless a force acting on them forces it to change this state (since there is no such thing as an object without force, this is not an experimental law), (using the ideal model method).

Newton's first law applies only to inertial frames of reference.

Newton's second law of motion states that the acceleration of an object is proportional to the net force experienced by the object and inversely proportional to the mass of the objectWhereas, the direction of the acceleration of the object is the same as that of the net force.

From the point of view of physics, Newton's second law of motion can also be expressed as the rate of change of momentum of an object with time is proportional to the sum of the external forces exerted on itThat is, the first derivative of momentum to time is equal to the sum of external forces.

where the net force (resultant) f and acceleration a are vectors (vectors) and masses m are pure (scalars).

The impulse theorem is derived from Newton's second theorem. But I think this formula is obtained through experiments, first to study the relationship between force and acceleration by determining mass, and then to study the relationship between acceleration and mass by determining force, so as to conclude that f is proportional to a, and a is inversely proportional to m.

It seems that there is no derivation formula.

According to the functional relationship between them, it is obtained: f am, and by adding the appropriate coefficient k between them, we get f=ma, k=1 because when the mass and acceleration of the object are 1, the force on the object is 1n, therefore, k=1

This formula is derived using the impulse theorem: the accumulation of the combined external force on the object in time is the increment of the impulse of the object.

Impulse formula: ft = ep

The impulse of the object: ep=mv

ft=△ep=mv-mv0=m(v-v0)

Your return is truly satisfying, and at the same time allows yourself to discover a fatal mistake in my own problem. It's a pity. That's when I wrote Newton's binomial theorem as Newton's second law in physics, but I still appreciate your wonderful return, after all, math and physics are very closely related.

Problem solving ideas: according to the slope of the graph line, the maximum acceleration during the movement of the trolley is obtained, and the change of the trolley acceleration is judged according to the force of the trolley

1) From the velocity time graph line, it can be seen that the slope of the first plot line is the largest, the acceleration is the largest, and the maximum acceleration a=vt

1m/s2＝

2) The curve changes from to , the slope of the graph line becomes smaller, and the acceleration decreases, because there is a hook code landing, and the resultant force on the car decreases

3) The resistance of the trolley can not be ignored, because after the first section of the hook code all landed, the trolley does a uniform deceleration linear motion

Therefore, the answer is: (1), (2) the following hook code lands, the resultant force of the trolley decreases, then the acceleration decreases (3) can not, because the trolley after the hook code lands, the friction force to do uniform deceleration linear motion

2. In the experiment of "verifying Newton's second law":

A student adopts the device as shown in Figure 1, the trolley with a mass of m = 1kg is placed on the horizontal track, and two sections of thin lines are hung with two identical hook codes After the trolley is released statically, the change relationship between the movement speed of the trolley and the time is measured by the displacement sensor, and the corresponding image is obtained on the computer screen According to the device diagram and the V-T image

1) The maximum acceleration during the movement of the trolley is about

2) The reason why the V-T image (Fig. 2) curve changes from to in motion of the trolley

3) Can the friction during the movement of the trolley be negligible? Why? __

Verification of Newton's second law: the magnitude of the acceleration of an object is proportional to the force, inversely proportional to the mass of the object, and proportional to the reciprocal of the mass of the object; The direction of acceleration is the same as that of the force acting on the collapse.

Newton's second law of motion applies only to particles. For the particle system, the isolation method is generally used when using Newton's second law of motion, or Newton's second law of the particle system is used.

Newton's second law of motion applies only to inertial frames of reference. The inertial frame of reference refers to the frame of reference in which Newton's laws of motion are established, and in non-inertial frames of reference, Newton's second law of motion does not apply. However, through the introduction of inertial forces.

It is possible to make the representation of Newton's second law of motion used in non-inertial frames.

Newton's second law of motion only applies to macroscopic problems. Quantum mechanics must be used to solve microscopic problems. When the linear degree of motion of an object can be compared with the de Broglie wave of the object, the momentum and position of the object cannot be accurately known at the same time due to the uncertainty relation of particle motion, so the Newtonian dynamics equation cannot be solved without accurate initial conditions.

Newton's second law of motion only applies to low-speed problems. The theory of relativity must be used to solve the high-speed problem. Since Newton's dynamical equations are not Lorentz covariant, they cannot be compatible with the special theory of relativity.

Therefore, when the object moves at high speed, it is necessary to modify the definition of mechanical variables such as force and velocity, so that the dynamic equation can meet the requirements of Lorentz covariance, and it will be different from classical mechanics in terms of physical prediction as the speed approaches the speed of light.

The method of accelerating the movement of sand and sand bucket through the thin line traction trolley was used, and the control variable method was used to study the relationship between the above two groups.

Through proper adjustment, the resistance of the trolley is ignored, and it can be obtained when m and m do acceleration motion.

When m is >> m, it can be approximated that the tensile force t on the trolley is equal to mg; In the first part of this experiment, the mass of the trolley is kept unchanged, the size of m is changed, the corresponding a is measured, and the relationship between a and f is verified. In the second part, the size of m is changed, and the acceleration a of the trolley motion is measured to verify the relationship between a and m.

Precautions for operation:

1) In Newton's second law experiment, the friction must be balanced by padding one end of the long plank, and the position of the pad should be appropriate after the position is determined, and the inclination angle can not be replaced.

2) When changing the size of m and m, every time the trolley starts to release, it should be as close as possible to the dot timer, and the trolley should be powered on first before putting the trolley.

3) Each time a is determined by paper tape, the average acceleration should be solved.

Newton's second law experiment is to verify Newton's second law of motion.

Newton's second law of motion is commonly formulated that the magnitude of an object's acceleration is proportional to the force, inversely proportional to the mass of the object, and proportional to the reciprocal of the mass of the object; The direction of acceleration is the same as that of the applied force.

This law was proposed by Isaac Newton in 1687 in his book Principles of Mathematics in Natural Philosophy. Newton's second law of motion and the first.

The first and third laws together constitute Newton's laws of motion, which expound the basic laws of motion in classical mechanics.

Brief introduction. Independence: The object is acted on by several external forces, and the acceleration produced under the action of one external force is only related to this external force, independent of other forces, and the vector sum of the acceleration produced by each force is equal to the acceleration produced by the resultant external force, and the resultant acceleration is related to the resultant external force.

Causality: Force is the cause of acceleration, acceleration is the effect of force, so force is the cause of changing the state of motion of an object.