Questions about the magnitude of the acceleration of the motion of a free fall

This is the analysis of some problems, the magnitude of the deceleration is not only related to the external force, but also related to the mass of the object, f=ma (Newton's second law) This is beyond doubt.

The greater the resultant external force, the greater the acceleration" is false, and it takes less into account the mass of the object.

Back to this question, for any free-falling object:

g-f=ma

So: a=(g-f) m=g-f m

The resistance experienced by the two balls during the falling process is equal, and the mass of the solid iron ball is larger, so the acceleration of the solid iron ball during the falling process is larger, according to h=1 2at 2, so the solid iron ball falls first. (In addition, it should be pointed out that the effect of air resistance is taken into account in the process of free fall in this question, so the process of falling is not a free fall motion).

This problem can be analyzed like this: in the process of free fall of the object, the object is only subject to the resistance of gravity and air, the solid ball and the hollow ball are in the same environment, so the resistance is the same, the resultant force is the gravity, a=g, the mass of the solid ball is greater than the hollow ball, so it lands first. When two objects have equal mass and equal air resistance, the greater the resultant force, the greater the acceleration.

That's about it.

The analysis is right, and your inference is wrong.

The volume is the same, the mass of a solid iron ball is greater than that of a hollow iron ball, but gravity = mass * gravitational acceleration. In the same place, the acceleration due to gravity is the same, for example, the acceleration has nothing to do with the magnitude of gravity, the greater the gravitational force is because of the large mass, if there is no air resistance, it is a free fall motion, and the fall time t=root number two (2h g)It's not about quality.

If there is air resistance, it will be understood according to the analytical method.

PS: If the volume is the same, the solid iron ball is more massive than the hollow iron ball, so the gravity is greater. If the volume is the same, the air resistance can be seen as the same. Air resistance is related to the shape of the object's motion.

You who said the amount of the parsing. Regardless of special circumstances, the acceleration caused by gravity on all objects on Earth is the same. That is, acceleration is a fixed value.

The velocity of a free fall varies with time and is calculated by the formula v=gt. where g is the acceleration due to gravity.

For, t refers to the time of free fall. Therefore, without considering the air resistance, if the initial velocity of the free fall is in seconds, and then the speed increases every second at any time.

Freefall movement.

Originating from gravity, the motion of an object falling from a relative rest under the action of gravity alone is called free fall motion (its initial velocity is vo = 0 m s), and then the speed increases due to acceleration for every 1 second increase in time. If you don't take into account any resistance, the speed will increase until infinity, but this is only an ideal state.

In fact, when the air is in free fall, the resistance of the air to the falling body gradually increases as the speed of the free fall increases. When the gravitational force experienced by the object is equal to the drag force it is experiencing, the falling body will fall at a uniform speed, and the maximum velocity it has reached at this point is known as the terminal velocity.

1.Both the buoyancy and drag of the air in the experiment have an impact on the results. Air buoyancy is an upward force formed due to the difference in pressure of a liquid or gas that can reduce the true weight of an object.

In experiments, if the air buoyancy Hu Shanfeng is not taken into account, the mass of the object will be overestimated. Whereas, drag is the force generated by the collision of a moving object with air, which will cancel out the speed of the object's motion, resulting in a slowdown in the falling speed of the object's pants. Therefore, if drag is not taken into account during the experiment, the resulting gravitational acceleration value will be lower than the real value.

2.When measuring gravitational acceleration using the free-fall method, you first make the object to fall freely, and then calculate the gravitational acceleration by measuring the fall time. The principle of this method is to take advantage of the effect of gravitational acceleration on the vertical free fall of an object.

In free fall, ignoring the influence of external forces such as air resistance and buoyancy, the falling speed of the object will continue to increase, and its acceleration is the gravitational acceleration. In order to reduce the error, it is necessary to use a precise timer and take measures to prevent the object from other external interference during the experiment.

Gravitational acceleration.

First, it is related to the factors of the earth, such as:

1. The position of the object on the ground.

For example, due to the rotation of the earth, gravity is a component of the earth's gravitational pull on an object, and another component is the centripetal force required to supply the object to rotate around the earth.

1) If the linear velocity of the object at the equator is large and the centripetal force required is large, the gravitational force will be small, and the gravitational acceleration will be small.

2) When going to the poles, the linear velocity of the object rotating with the earth becomes smaller, and the centripetal force required becomes smaller, and the gravitational force is divided, and the gravitational acceleration becomes larger.

3) When the pole is reached, the linear velocity of the object rotating with the earth is the smallest, and the centripetal force required is the smallest, then the gravitational force is the largest, and the gravitational acceleration is the largest.

2. The higher the height of the object from the ground, the smaller the gravitational acceleration, because gravity is a component of the gravitational force of the earth on the object, and the main component of this gravitational force is gravity, the magnitude of the gravitational force is inversely proportional to the square of the distance, the higher the object is from the ground, the greater the distance between the object and the center of the earth, the smaller the gravitational force, the smaller the gravitational force, so the smaller the acceleration;

3. If it is a deep hole in the ground, the deeper it is, the smaller the gravitational acceleration, and when the object is at the center of the earth, the gravitational acceleration is theoretically "0", which is obtained according to the principle of theoretical mechanics.

Second, it is related to the attraction of alien stars, such as the attraction of the sun and the moon to the earth, which reduces the gravitational force of the object and makes the gravitational acceleration smaller.

It depends on how long it hits the ground, if the time is t, the landing speed is v, and the impact force is f. It can be calculated using the formula ft=mv.

An object that falls without any drag and only under the action of gravity is called"Free fall"。Such as an object that begins to fall from a resting state under the gravitational pull of the earth. The sky above the Earth's surface can be seen as a constant gravitational field.

Without taking into account atmospheric drag, the free fall motion in this region is a uniformly accelerated linear motion. Its acceleration is constant equal to the acceleration g due to gravity.

Although the gravitational force of the Earth is inversely proportional to the square of the distance from the object to the center of the Earth, the radius of the Earth is much larger than the distance traveled by the free fall, so the gravitational force near the ground can be regarded as constant for the lead, and the acceleration of the free fall is an invariant constant. It is a uniformly accelerated linear motion with zero muzzle velocity.

The first to study free fall was the ancient Greek scientist Aristotle, who proposed that the speed of falling an object is determined by the weight of the object itself, and the heavier the object, the faster it falls; Conversely, the slower it falls. Aristotle's theories influenced people for more than 2,000 years.

Until the physicist Galileo Galilei came up with the opposite opinion. In his 1636 Dialogue between Two New Sciences, Galileo wrote: If, according to Aristotle's theory, suppose there are two stones, the larger one weighs 8 and the smaller one 4, then the large one falls at a speed of 8 and the small one falls at a speed of 4, and when two stones are tied together, the faster one will be slowed down because the one is slow.

So the whole potato farming system and the falling speed are between 4-8.

However, the overall weight of the two stones tied together is 12, and the falling speed should be greater than 8, which falls into a paradoxical realm. From this, Galileo deduced that the speed at which an object falls should not be determined by its weight. In the book, he envisions that the speed of free fall changes at a uniform speed.

Free fall velocity: final velocity v=gt, initial velocity vo=0. Fall height h=gt meters and seconds (acceleration due to gravity), t is the fall time.

Free Fall Calculation Formula

The formula for calculating the instantaneous velocity of a free fall is v=gt; The displacement is calculated as s=gt 2, where s is the distance increment, g is the acceleration due to gravity (g = m s2, usually 10m s2), and t is the time when the object falls.

Freefall movement.

1.Muzzle velocity vo=0

2.End velocity v=gt

3.Drop height h=gt2 (calculated from VO position downwards).

4.The general formula vt = 2gh

5.Inference vt = 2h

Note: (1) The free fall motion is a uniform acceleration linear motion with zero initial velocity, which follows the law of uniform linear motion with variable speed.

2) g The gravitational acceleration is smaller near the equator and smaller than flat land in high mountains, and the direction is straight down).

The law of free fall derives kinetic energy

This is because the distance of the object falling in 1s is: times of the acceleration in 1s (the average velocity of this distance) multiplied by time, and the kinetic energy of the object is = the work done by the gravitational fall of the object = and then deforms the above formula: e kinetic energy = indicate g = a, a is the acceleration of the object) = the velocity of the object in free fall is time * acceleration) = .