An intuitive free-fall motion experimental device and experimental method

Abstract

The invention discloses an intuitive free-fall motion experimental device and an experimental method, comprising a crossbeam (6) installed on a right column (11) and a left column (5), an A rod (8) and a B rod (9) inserted into a horizontal long hole (10) in the middle of the crossbeam (6), a lower rod (15) installed in a vertical long hole (16) in the middle of the right column (11), a metal plate (4) suspended on the A rod (8) through an A line (13), the other end of the A line (13) passing around the A rod (8) and After passing through the lower rod (15), the wire is clamped with a wire clamp (17). A metal ball (2) is suspended on the B rod, and the rightmost spherical surface of the metal ball (2) is connected to the C wire (3). The other end of the C wire (3) is pulled through the lower rod (15) and clamped with the wire clamp (17). The A wire (13) and the C wire (3) are cut at the lower rod (15) with scissors. The falling distance of the metal plate (4) and the time of a quarter of the swing cycle of the metal ball (2) are recorded to obtain the value of acceleration a.

Description

Technical Field

[0001] The invention relates to a physical experiment device, in particular to an intuitive free-fall motion experiment device and an experiment method. Background Art

[0002] In middle school physics teaching, free fall is an important learning content. According to Galileo's research results, free fall is a uniformly accelerated linear motion with an initial velocity of zero. It is directly pointed out that the acceleration of all objects in free fall is the same. This acceleration is called free fall acceleration, also called gravity acceleration, usually expressed in g. In common calculations, the g value can be taken as 9.8m / s 2 However, directly telling students the magnitude of gravitational acceleration in teaching will make it difficult for students to be convinced, and they will not be able to have a deep understanding of the concept of gravitational acceleration. Middle school physics needs to train students' visual thinking ability, and through observation of phenomena and demonstration experiments, students can establish physical concepts, understand its laws, and acquire qualitative knowledge.

[0003] The displacement formula for free fall is

[0004]

[0005] Students need the most direct way to verify the above formula and measure the value of acceleration a. However, some existing methods for measuring gravity acceleration require indirect measurement and understanding, while others require complex modern measuring instruments. The devices are very complicated and there is no intuitive method to directly verify that the acceleration a of a free-falling body is the gravity acceleration g through the relationship between the distance and time of free fall of an object, and g = 9.8m / s 2 . Summary of the invention

[0006] The purpose of the present invention is to provide an intuitive free fall motion experimental device and experimental method, which are used to directly verify the displacement formula of free fall motion, are suitable for experimental teaching for beginners, and directly calculate the value of gravitational acceleration through the relationship between free fall displacement and time.

[0007] The objective of the present invention is achieved through the following technical solutions:

[0008] An intuitive free fall motion experimental device and experimental method Figure 1 As shown, it includes a base 1, a metal ball 2, a C wire 3, a metal plate 4, a left column 5, a crossbeam 6, an A rod 8, a B rod 9, a horizontal long hole 10, a right column 11, a B wire 12, an A wire 13, a nut 14, a lower rod 15, a vertical long hole 16, and a wire clamp 17.

[0009] The base 1 is in the shape of a long metal plate, with a left column 5 vertically fixedly installed on the left side of the base 1, and a right column 11 vertically fixedly installed on the right side of the base 1, and a crossbeam 6 fixedly installed on the top ends of the left column 5 and the right column 11.

[0010] The crossbeam 6 is a rectangular metal strip with a horizontal long hole 10 in the middle of the metal strip. The A rod 8 and the B rod 9 are inserted into the horizontal long hole 10. The A rod 8 and the B rod 9 can slide horizontally in the horizontal long hole 10 and are fixed at any position in the horizontal long hole 10 by a nut 14. Figure 2 shown.

[0011] A vertical long hole 16 is processed in the middle of the right column 11, and a lower rod 15 is installed in the vertical long hole 16. The lower rod 15 can slide up and down in the vertical long hole 16, and the lower rod 15 can be fixed at any position in the vertical long hole 16 by a nut.

[0012] A wire clamp 17 is installed at the lower part of the vertical long hole 16 .

[0013] The metal plate 4 is suspended on the A rod 8 , one end of the A wire 13 is connected to the center of the upper end of the metal plate 4 , and the other end is clamped by the wire clamp 17 after passing through the A rod 8 and the lower rod 15 .

[0014] A metal ball 2 is suspended on the B rod, one end of the B line 12 is connected to the metal ball 2, and the other end is directly connected to the B rod 9.

[0015] The metal plate 4 is 60-70cm long and 8-10cm wide. After being suspended on the A rod 8, the bottom end height is lower than the height of the lower rod 15. After the metal ball 2 is suspended on the B rod, when it swings along the plane parallel to the left column 5 and the right column 11 with the B rod as the center, the rightmost spherical surface of the metal ball can just contact the lower rod 15.

[0016] The rightmost spherical surface of the metal ball 2 is connected to the C line 3. After the other end of the C line 3 is pulled around the lower rod 15, the C line 3 is clamped by the wire clamp 17 when the right spherical surface of the metal ball 2 contacts the lower rod 15.

[0017] The A-wire 13, B-wire 12 and C-wire 3 are all made of thin wires with high strength and low friction resistance;

[0018] Preferably, the A line 13 is made of high-strength nylon wire with a wire diameter of 0.5 mm, and the B line 12 and the C line 3 are made of rubber wire with a wire diameter of 0.3 mm. Both wires are available on Taobao.

[0019] Measurement method: (1) Using the above device, set the length of line B 12 to a certain value, apply a little red ink on the leftmost spherical surface of metal ball 2, measure the swing period of metal ball 2 without connecting line C 3, then move metal plate 4 close to and just touch metal ball 2, print a red dot on the lower end of the surface of metal plate 4, then connect line C 3 to metal ball 2, pull line C 3 around lower rod 15, so that metal ball 2 is close to lower rod 15 and then clamped with wire clamp 17. (2) Use scissors to cut line A 13 and line C 3 at the lower rod 15 at the same time. Metal plate 4 falls and metal ball 2 swings back to the equilibrium position. After swinging for a quarter of a cycle, metal ball 2 collides with the falling metal plate 4, and a red dot is printed on metal plate 4 again. The distance between the two red dots on metal plate 4 is the distance that metal ball 2 falls in a quarter of a cycle. According to The acceleration a value can be calculated, which is the gravitational acceleration value g = 9.8m / s 2 .

[0020] It can be seen from the technical solution provided by the present invention that the beneficial effects of the intuitive free fall motion experimental device and experimental method provided by the embodiment of the present invention are: (1) the relationship between the displacement and time of the free fall motion can be directly demonstrated, and the value of the gravitational acceleration can be calculated through the relationship between the free fall displacement and time. The physical meaning is clear and definite, and the image is intuitive, which is suitable for teaching experiments for beginners; (2) the experiment is convenient and fast, and can be used as a group experiment for students or as a classroom teaching demonstration experiment; (3) the experimental device has a simple structure, is easy to make, and has low cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 A schematic structural diagram of an intuitive free-fall motion experimental device and experimental method provided in an embodiment of the present invention.

[0022] Figure 2 A schematic rear view of a beam of an intuitive free fall motion experimental device and experimental method provided in an embodiment of the present invention.

[0023] In the figure: 1. base, 2. metal ball, 3. C line, 4. metal plate, 5. left column, 6. beam, 7. beam scale, 8. A rod, 9. B rod, 10. horizontal long hole, 11. right column, 12. B line, 13. A line, 14. nut, 15. lower rod, 16. vertical long hole, 17. wire clamp. DETAILED DESCRIPTION

[0024] The technical solutions in the embodiments of the present invention are described clearly and completely below in conjunction with the accompanying drawings in the embodiments of the present invention.

[0025] The base 1 is the foundation of the whole device, and is in the shape of a long metal plate. The left side of the base 1 is fixedly installed with a left column 5 vertically upward, and the right side of the base 1 is fixedly installed with a right column 11 vertically upward. The top of the left column 5 and the right column 11 is fixedly installed with a crossbeam 6, and the whole constitutes a door-shaped bracket. The crossbeam 6 is a rectangular metal strip, and the middle of the metal strip has a horizontal long hole 10, and the A rod 8 and the B rod 9 are inserted into the horizontal long hole 10. The A rod 8 and the B rod 9 can slide horizontally in the horizontal long hole 10 and are fixed at any position in the horizontal long hole 10 by a nut 14; the middle of the right column 11 is processed with a vertical long hole 16, and the lower rod 15 is installed in the vertical long hole 16. The lower rod 15 can slide up and down in the vertical long hole 16, and the lower rod 15 can be fixed at any position in the vertical long hole 16 in the same way as the nut 14 on the A rod 8 and the B rod 9.

[0026] A wire clamp 17 is installed at the lower part of the vertical long hole 16. The wire clamp 17 is made of wood material and can clamp the thin wire.

[0027] The metal plate 4 is suspended on the A rod 8, one end of the A wire 13 is connected to the center of the upper end of the metal plate 4, and the other end passes around the A rod 8 and the lower rod 15 and is clamped and fixed with a wire clamp 17, so as to ensure that the suspended metal plate 4 remains vertical to the horizontal plane.

[0028] A metal ball 2 is suspended on the B rod, one end of the B line 12 is connected to the metal ball 2, and the other end is directly connected to the B rod 9.

[0029] In order to reduce the influence of air resistance and collide with the metal ball 2 during falling, the length of the metal plate 4 is 60-70 cm and the width is 8-10 cm. Moreover, after being suspended on the A rod 8, the height of the bottom end is slightly lower than the height of the lower rod 15, so as to ensure that the metal ball 2 can contact the lower end of the metal plate 4 after being suspended on the B rod, and the right spherical surface of the metal ball can just contact the lower rod 15 when swinging along the plane parallel to the left column 5 and the right column 11 with the B rod as the center.

[0030] During the experiment, the C line 3 is connected to the rightmost spherical surface of the metal ball 2, and after the other end of the C line 3 is pulled around the lower rod 15, the C line 3 is clamped by the wire clamp 17 when the right spherical surface of the metal ball contacts the lower rod 15.

[0031] The A wire 13, B wire 12 and C wire 3 are all made of thin wires with high strength and low friction resistance. The suspended metal plate 4 is heavy, so the A wire 13 uses high-strength nylon wire with a wire diameter of 0.5mm. The B wire 12 and C wire 3 are only used to suspend the metal ball 2. The force is very small, so a rubber wire with a wire diameter of 0.3mm is used. The surface of nylon wire and rubber wire is smooth, and the impact on moving parts is minimal. Both types of wires can be bought on Taobao.

[0032] The beam scale 7 serves as a reference for the movement of the A rod 8 and the B rod 9 and the swing angle of the metal ball 2.

[0033] 1. Classroom Demonstration Experiment

[0034] (1) Using the above device, set the length of line B 12 to a certain value, apply a little red ink on the left side of the metal ball 2, measure the swing period of the metal ball 2 without connecting line C 3, then move the metal plate 4 close to and just touch the metal ball 2, print a red dot on the lower end of the surface of the metal plate 4, then connect line C 3 to the metal ball 2, pull line C 3 around the lower rod 15, so that the metal ball 2 is close to the lower rod 15 and then clamped with the wire clamp 17. (2) Use scissors to cut line A 13 and line C 3 at the lower rod 15 at the same time. The metal plate 4 falls and the metal ball 2 swings back to the equilibrium position. After a quarter of a cycle of swing, the metal ball 2 collides with the falling metal plate 4, and a red dot is printed on the metal plate 4 again. The distance between the two red dots on the metal plate 4 is the distance the metal ball 2 falls in a quarter of a cycle of swing. According to The acceleration a value can be calculated, which is the gravitational acceleration value g = 9.8m / s 2 .

[0035] The measurement method of one quarter period is as follows: the period of a simple pendulum is only related to the length of the pendulum, so when the pendulum length is determined, the metal plate 4 can be removed, and the total time used for 20 periods can be measured with a stopwatch, and then averaged to one quarter period, which is very accurate. If students have not learned the principle of a simple pendulum, but the isochronism of the pendulum has been mastered by elementary school students in common sense classes and extracurricular activities, they only need to know how to measure the period of the pendulum.

[0036] 2. Group experiment

[0037] (1) Fix the length of line B 12, keep the initial position of the red dot of metal ball 2 on metal plate 4 unchanged, repeat the steps of "1. Classroom demonstration experiment" 3-4 times, and take the average of the distance between the upper and lower red dots each time. Then use the formula Calculating the value of gravitational acceleration can greatly improve the accuracy.

[0038] (2) Change the length of line B 12, such as changing the pendulum length to 30cm, 40cm, 50cm, etc., and the position of the metal plate 4 changes with the length of line B 12. Repeat the steps of "1. Classroom demonstration experiment" and take the average value of the gravity acceleration measured each time to improve the measurement accuracy. At this time, it is necessary to adjust the position of the lower rod 15 to ensure that when the line C 3 is pulled, the right spherical surface of the metal ball 2 can just contact the lower rod 15. Use scissors to cut the line A 13 and the line C 3 at the lower rod 15 at the same time. The silk thread on the metal ball 2 is very short and will not affect the movement of the metal ball 2. That is, the motion cycle error caused by this is very small and can be ignored.

[0039] In the experiment, the metal plate 4 needs to be perpendicular to the plane where the left column 5 and the right column 11 are located. You can first hold it still for a while with your hands and then use scissors to cut the A line 13 and the C line 3 at the lower rod 15 at the same time. The metal plate 4 falls and the metal ball 2 swings back to the equilibrium position. In this extremely short time of a quarter cycle, the metal plate 4 will not deflect anymore, and the metal ball 2 will not rotate significantly, which can ensure that the metal ball 2 collides head-on with the metal plate 4 and prints a red dot on the metal plate 4.

[0040] A quarter of a period of movement of the metal ball 2 is selected to measure the falling distance of the metal plate 4. First, this position is clear. As long as the metal plate 4 is just in contact with the metal ball 2 when the metal ball 2 is in the equilibrium position, the movement time of the metal ball 2 is exactly a quarter of a period when the metal ball 2 swings back from the initial position and collides with the falling metal plate 4. Second, at this position, the metal ball has enough energy to collide with the metal plate 4, leaving a clear mark.

[0041] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by any technician familiar with the technical field within the technical scope disclosed in the present invention should be covered within the protection scope of the present invention.

Claims

1. An intuitive free fall motion experimental device, characterized in that: It comprises a base (1), a metal ball (2), a C wire (3), a metal plate (4), a left column (5), a crossbeam (6), an A rod (8), a B rod (9), a horizontal long hole (10), a right column (11), a B wire (12), an A wire (13), a nut (14), a lower rod (15), a vertical long hole (16), and a wire clamp (17); The base (1) is in the shape of a long metal plate, a left column (5) is fixedly installed vertically upward on the left side of the base (1), a right column (11) is fixedly installed vertically upward on the right side of the base (1), and a crossbeam (6) is fixedly installed at the top ends of the left column (5) and the right column (11); The crossbeam (6) is a rectangular metal strip with a horizontal long hole (10) in the middle of the metal strip. The A rod (8) and the B rod (9) are inserted into the horizontal long hole (10). The A rod (8) and the B rod (9) can slide horizontally in the horizontal long hole (10) and are fixed at any position in the horizontal long hole (10) by a nut (14); A vertical long hole (16) is processed in the middle of the right column (11), and a lower rod (15) is installed in the vertical long hole (16). The lower rod (15) can slide up and down in the vertical long hole (16), and the lower rod (15) can be fixed at any position in the vertical long hole (16) by a nut; A wire clamp (17) is installed at the lower part of the vertical long hole (16); A metal plate (4) is suspended on the A rod (8), one end of an A wire (13) is connected to the center of the upper end of the metal plate (4), and the other end passes around the A rod (8) and the lower rod (15) and is clamped by a wire clamp (17); A metal ball (2) is suspended on the B rod, one end of the B wire (12) is connected to the metal ball (2), and the other end is directly connected to the B rod (9); After the metal ball (2) is suspended on the B rod, when it swings with the B rod as the center along the plane parallel to the left column (5) and the right column (11), the rightmost spherical surface of the metal ball can just contact the lower rod (15); The rightmost spherical surface of the metal ball (2) is connected to a C line (3), and after the other end of the C line (3) is pulled around the lower rod (15), the C line (3) is clamped by a wire clamp (17) when the right spherical surface of the metal ball (2) contacts the lower rod (15).

2. The intuitive free fall motion experimental device according to claim 1, characterized in that: The measuring method when using the above device is as follows: I. The length of the B line (12) is set to a certain value, a little red ink is applied to the left spherical surface of the metal ball (2), and the swing period of the metal ball (2) is measured without connecting the C line (3). Then, the metal plate (4) is moved close to and just touches the metal ball (2), and a red dot is printed on the lower end of the surface of the metal plate (4). Then, the C line (3) is connected to the metal ball (2), and the C line (3) is pulled around the lower rod (15) so that the metal ball (2) After being pressed against the lower rod (15), it is clamped with a wire clamp (17); II. Using scissors, the A wire (13) and the C wire (3) are cut at the lower rod (15) at the same time. The metal plate (4) falls and the metal ball (2) swings back to the equilibrium position. After swinging for a quarter of a cycle, the metal ball (2) collides with the falling metal plate (4), and a red dot is printed on the metal plate (4) again. The distance between the two red dots on the metal plate (4) is the distance that the metal ball (2) falls in a quarter of a cycle. According to The acceleration a value can be calculated, which is the gravitational acceleration value g = 9.8m / s 2 .

3. The intuitive free fall motion experimental device according to claim 1, characterized in that: The metal plate (4) has a length of 60-70 cm and a width of 8-10 cm. After being suspended on the A rod (8), the height of the bottom end is lower than the height of the lower rod (15).

4. The intuitive free fall motion experimental device according to claim 1, characterized in that: The A-wire (13), B-wire (12) and C-wire (3) are all made of fine wires with high strength and low friction resistance.

5. The intuitive free fall motion experimental device according to claim 1, characterized in that: The wire clamp (17) is made of wood material and can clamp the thin wire.

6. The intuitive free fall motion experimental device according to claim 1, characterized in that: The crossbeam (6) is provided with a crossbeam scale (7).

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