newton's first law apparatus

Abstract

The application discloses a Newton first law experiment instrument, which comprises a base (1), a vertical upward fixed long tube (2) on one side of the base (1), a cover (5) on the upper end of the long tube (2), a center hole (6) on the cover (5), a fixed pulley (7) installed on one side of the center hole (6), a suspension body (3) placed in the long tube (2), a thin rope (4) connected to the upper end of the suspension body (3), the other end of the thin rope (4) passing through the round hole (6) on the cover (7) and winding around the fixed pulley (7) and then suspending a weight (8) at the lower end, the inside of the long tube (2) being filled with liquid, the thin rope (4) pulling the weight (8) to rise to the top end height position of the long tube (2) when the suspension body (3) sinks to the bottom position of the long tube (2) in the liquid, the weight (8) being put back to the bottom position of the long tube (2) by the thin rope (4) when the suspension body (3) is at the top position of the long tube (2), and the running speed of the suspension body (3) being measured by a photoelectric gate speed measuring device.

Description

Technical Field

[0001] This invention relates to a physical experimental apparatus, and more particularly to an experimental apparatus for Newton's first law. Background Technology

[0002] In high school physics teaching, Newton's First Law is an important subject. Newton's First Law states that every object, when not acted upon by a force (when the net external force is zero), will continue in its state of rest or uniform motion in a straight line unless compelled to change that state of motion by an action on it.

[0003] Because of Earth's gravity, objects without external forces do not exist. Therefore, a crucial aspect of verifying Newton's First Law is demonstrating that an object maintains uniform linear motion when acted upon by a net force of zero. Due to friction, it's difficult to achieve a purely uniform linear motion. A common and relatively accurate method uses an air track, allowing a small car to pass through different photogates in the same amount of time, demonstrating that under conditions of minimal friction and negligible air resistance, the car approximates uniform linear motion. However, this method has several drawbacks: firstly, it requires large equipment and a dedicated space; secondly, it generates significant noise, impacting the environment and the effectiveness of the teaching experiment; and thirdly, the results are inaccurate because the car is not actually moving at a uniform speed. The photogates measure the car's speed at different points in its path, and due to the significant influence of friction and air resistance, the time taken for the car to pass through each photogate's location is not equal, sometimes with substantial discrepancies, making it difficult for students to believe the car is moving at a uniform speed. Summary of the Invention

[0004] The purpose of this invention is to provide an experimental apparatus for Newton's first law, which is used to verify that an object always maintains a uniform linear motion when subjected to a net external force of zero, thereby accurately verifying Newton's first law.

[0005] The objective of this invention is achieved through the following technical solution:

[0006] Newton's First Law Experiment Apparatus Figure 1 As shown, it includes a base 1, a long tube 2, a suspension body 3, a thin rope 4, a cover 5, a round hole 6, a fixed pulley 7, a weight 8, and a photoelectric gate speed measuring device.

[0007] The base 1 is a long metal plate. A long tube 2 is fixed vertically upward on one side of the base 1. The upper end of the long tube 2 is equipped with a cover 5. The cover 5 has a central hole 6. A fixed pulley 7 is installed on one side of the central hole 6.

[0008] The suspension body 3 is placed inside the long tube 2. The upper end of the suspension body 3 is connected to the thin rope 4. The other end of the thin rope 4 passes through the round hole 6 on the cover 7 and goes around the fixed pulley 7 before the lower end is suspended by the weight 8.

[0009] The long tube 2 is a thick-walled cylindrical tube made of glass, with an inner diameter of 3-4 cm and a height of 80-100 cm.

[0010] The long tube 2 is filled with liquid. When the suspension body 3 sinks to the bottom of the long tube 2 in the liquid, the thin rope 4 pulls the weight 8 up to the top of the long tube 2. When the suspension body 3 is at the top of the long tube 2, the weight 8 is put back to the bottom of the long tube 2 by the thin rope 4.

[0011] The suspension body 3 includes a cylinder 13 and a cylindrical body 14, such as... Figure 2 As shown, the cylinder 13 is a thin-walled metal cylinder, which is connected to the metal cylinder 14 by a spiral inside. The center point of the upper surface of the cylinder 14 is connected to the thin rope 4, and the bottom surface and the side surface are made into arc surfaces. The running speed of the suspension body 3 is measured by the photoelectric gate speed measuring device.

[0012] The aforementioned photoelectric gate speed measuring device includes photoelectric gate A 9, column 10, photoelectric gate B 11, and movable base 12.

[0013] The movable seat 12 is a metal disc that can be placed on the base 1 and moved. The center of the movable seat 12 is vertically fixed to the column 10, which is marked with a scale. A photoelectric gate 9 and a photoelectric gate 11 are installed on the column 10 from top to bottom. Each photoelectric gate can move freely on the column 10, and the distance between the two photoelectric gates can be read through the scale.

[0014] When the A photoelectric gate 9 and B photoelectric gate 11 are used for measurement, their inner rings are placed outside the long tube 2 and are both connected to the timing device.

[0015] As a preferred option, the timing device is selected as the HA8-J0201-CC type digital timer, with an operating power supply of AC 220±10%V 50Hz, a timing accuracy of 0.1ms, and 2 detection probes.

[0016] The HA8-J0201-CC digital timer has an "S1" timing mode: timing starts when any photoelectric gate is blocked and stops when the blocking ends. The instrument screen displays the number of blocking times and the blocking time in sequence.

[0017] The concave groove of the fixed pulley 7 is vertically aligned with the center of the circular hole 6 on the cover 5, so that when the suspended body 3 falls into the bottom of the long tube 2, the thin rope 4 coincides with the axis of the long tube 2 and will not come into contact with the circular hole 6 on the cover 5. Figure 1 As shown.

[0018] The suspension body 3 passes through the light-emitting device and the receiving device of the two photoelectric gates inside the long tube 2, and the suspension body 3 can block the light emitted by the light-emitting device.

[0019] When using the experimental apparatus for Newton's first law, the liquid medium inside the long tube 2 can be a transparent liquid such as water or oil.

[0020] As can be seen from the above technical solution provided by the present invention, the beneficial effects of the Newton's First Law Experimental Instrument provided by the embodiments of the present invention are as follows: (1) When the suspended body 3 falls in the liquid in the long tube, the motion of the suspended body 3 or the weight 8 is a real linear uniform motion. Newton's First Law can be verified by the photoelectric gate timing device. The structure is simple, the operation is reliable, and there is no noise. (2) The experimental effect is clear and obvious. It can be used as a demonstration experiment or as a group quantitative experiment measurement for students. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of the experimental apparatus for Newton's first law provided in an embodiment of the present invention.

[0022] Figure 2 A schematic diagram of the suspension structure of the experimental apparatus for Newton's first law provided in an embodiment of the present invention.

[0023] Figure 3 A schematic diagram of the force analysis of the suspension body of the Newton's First Law experimental apparatus provided in an embodiment of the present invention.

[0024] Figure 4 This is a schematic diagram of the uniform motion measurement of weights in the Newton's First Law experimental apparatus provided in an embodiment of the present invention.

[0025] In the diagram: 1. Base, 2. Long tube, 3. Suspended ball, 4. Thin rope, 5. Cover, 6. Round hole, 7. Fixed pulley, 8. Weight, 9. A photoelectric gate, 10. Column, 11. B photoelectric gate, 12. Movable seat, 13. Cylinder, 14. Cylinder body. Detailed Implementation

[0026] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention.

[0027] First, add the prepared machine oil or water into the long tube 2 until it is slightly below the opening of the long tube 2. Then, let the thin rope 4 on the suspension body 3 pass through the round hole 6 on the cover 5, go around the fixed pulley 7 and suspend the weight 8. Place the suspension body 3 in the liquid inside the long tube 2, and then put the cover 5 on the long tube 2 to fix it.

[0028] 1. The principle of uniform motion of the suspended body 3

[0029] like Figure 2As shown, the suspended body 3 is placed inside a long tube 2 filled with liquid and falls. The forces acting on it are as follows:

[0030] F1 is the resultant force of the upward pulling force on the suspension body 3, directed upwards. It includes the weight of the weight 8 and the frictional resistance of the rotating fixed pulley 7.

[0031] F2 includes the viscous resistance of the liquid, the buoyancy of the suspension body 3 in the liquid, and the motion resistance of the suspension body 3 on the suspension body 3 formed by the annular throttling orifice formed by the suspension body 3 and the inner wall of the long tube 2, which is in the upward direction.

[0032] The effect of the throttle orifice on the descent of suspension body 3:

[0033] Orifices are a very common basic component in hydraulic systems. Their main function is to change the pressure difference before and after a pipeline, thereby controlling the flow rate, pressure, and other characteristic quantities of the fluid in the system. The most important parameters are the throttling area (orifice diameter) and the throttling length.

[0034] (1) When the suspended body 3 falls, a pressure difference is formed between its upper and lower surfaces. The magnitude of the pressure difference is proportional to the liquid flow velocity of the throttling orifice. Under the condition that the throttling area remains unchanged, the faster the suspended body 3 falls, the greater the liquid flow velocity, the greater the pressure on the bottom of the suspended body 3, that is, the greater the resistance to the fall of the suspended body 3; (2) The smaller the diameter of the throttling orifice (the smaller the throttling area), the greater the resistance to the fall of the suspended body 3; (3) The greater the throttling length, the greater the resistance to the fall of the suspended body 3. Rotating the cylinder 14 in the suspended body 3 downwards increases the throttling length of the liquid, which has a great influence on the speed of the fall of the suspended body 3.

[0035] F is the weight of the suspended body 3, directed downwards.

[0036] When the suspended body 3 falls in the liquid, the three forces it experiences are all in the vertical direction, while the forces in the horizontal direction cancel each other out.

[0037] When F > F1 + F2, the suspended body 3 accelerates its fall in the liquid. However, the viscous resistance of the liquid in F2 and the resistance of the throttling orifice formed by the suspended body 3 and the cylindrical tube 2 increase with the increase of the falling speed of the suspended body 3. The suspended body 3 starts to accelerate from rest. When the falling speed of the suspended body 3 reaches a certain magnitude, the sum of these three forces is equal to zero, that is, F1 + F2 = F. Thus, the suspended body 3 begins to fall at a constant speed.

[0038] The falling speed of the suspended body 3: The maximum falling speed of the suspended body 3, which is the uniform linear motion speed of the suspended body 3, depends on the difference between F and the sum of F1+F2.

[0039] Therefore, by selecting appropriate parameters, such as the geometric dimensions and weight of the suspended body 3, the inner diameter of the long tube 2, the viscosity coefficient of the liquid, and the weight of the weight 8, the movement of the suspended body 3 inside the cylindrical tube 2 is such that the initial small segment is an accelerated motion, while the rest is a uniform descent.

[0040] Before the formal measurement, it is necessary to roughly determine the position where the suspended body 3 reaches equilibrium under the force of its fall. Specifically, place the suspended body 3 at the center of a long tube 2 filled with liquid. The suspended body 3 will fall freely within the liquid, starting with an initial velocity of zero and gradually increasing in speed. When the speed reaches its maximum value, the net external force on the suspended body 3 becomes zero, and it begins to move at a constant velocity in a straight line. The position where the suspended body 3 begins to move at a constant velocity in the liquid can be determined by observation (precise accuracy is not required). At this point, draw a horizontal line on the long tube 2. Then adjust photogates A (9) and B (11) below this horizontal line, maintaining a distance of approximately 20 cm between the two photogates. Note that as the suspended body 3 approaches the bottom of the long tube 2, the viscous resistance of the liquid gradually increases due to the compression effect of the bottom of the tube. The net external force on the suspended body 3 is no longer zero, and it is no longer in a state of uniform linear motion. Therefore, photogate B (11) should be at least 5 cm above the bottom of the long tube 2.

[0041] Set the HA8-J0201-CC digital timer to "S1". When the suspended body 3 passes through photogate A 9, timing begins when light is blocked and stops when light blocking ends. The suspended body 3 then passes through photogate B 11, again starting timing when light is blocked and stopping when light blocking ends. The instrument screen displays the number of times light is blocked and the duration of the blocking, showing that the blocking time is equal when the ball passes through both photogates. Therefore, the height of the suspended body 3 divided by the blocking time gives its running speed. Since the running speed of the suspended body 3 is equal when passing through photogate A 9 and photogate B 11, the net external force acting on the suspended body 3 is zero when its falling speed reaches its maximum, and the suspended body 3 maintains this speed in uniform linear motion.

[0042] If the speed at which the suspended body 3 falls is too fast or too slow, the suspended body 3 can be adjusted by rotating the cylinder 14 downwards and extending it out of the cylinder 13. This increases the throttling length and can significantly change the falling speed of the suspended body 3, so that the uniform motion speed of the suspended body 3 meets the requirements for observation and measurement.

[0043] When measuring the speed of the suspended body 3, the beam of the photoelectric gate should avoid the position of the thin rope 4 to avoid affecting the light-blocking speed measurement.

[0044] As can be seen from the technical solutions provided by the present invention above, the experimental apparatus for Newton's first law provided by the embodiments of the present invention has the following characteristics:

[0045] (1) When the suspended body 3 falls freely and reaches equilibrium, the net external force it receives is zero. The object being measured is not making an approximate uniform motion, but is actually making a uniform linear motion. The digital timing device has high precision. Therefore, the device of this invention can accurately verify Newton's first law and can be used as a general device for generating uniform linear motion in other experiments.

[0046] (2) The speed of the weight 8 can be directly measured. The uniform speed of the weight 8 is equal in magnitude and opposite in direction to the speed of the suspension body 3, which is more convenient. Figure 4 As shown.

[0047] (3) When the suspended body 3 falls freely in the liquid, because the diameter of the suspended body 3 is relatively large, it ensures that the light emitted by the photoelectric gate light-emitting device when the suspended body 3 falls can accurately realize the time of light blocking and work reliably.

[0048] This experimental apparatus can accurately prove Newton's first law, which states that every object, when not acted upon by a force (when the net external force is zero), will remain in a state of uniform rectilinear motion or at rest.

[0049] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention.

Claims

1. Newton's first law apparatus, characterized in that, It comprises a base (1), a long tube (2), a hanging body (3), a thin rope (4), a cover (5), a round hole (6), a fixed pulley (7), a weight (8) and a photoelectric gate speed measuring device. The base (1) is a metal long plate, and the long tube (2) is fixed vertically upward on one side of the base (1); the long tube (2) is provided with the cover (5) on the upper end, and the cover (5) is provided with the central hole (6); the fixed pulley (7) is installed on one side of the central hole (6). The hanging body (3) is arranged in the long tube (2), and the upper end of the hanging body (3) is connected with the thin rope (4); the other end of the thin rope (4) passes through the round hole (6) of the cover (5) and is wound around the fixed pulley (7) and then is hung with the weight (8) at the lower end. The long tube (2) is a thick-walled cylinder made of transparent glass, with an inner diameter of 3-4 cm and a height of 80-100 cm. The long tube (2) is filled with liquid; when the hanging body (3) sinks to the bottom of the long tube (2) in the liquid, the thin rope (4) pulls the weight (8) to rise to the top of the long tube (2); when the hanging body (3) is at the top of the long tube (2), the weight (8) is released by the thin rope (4) to the bottom of the long tube (2); the running speed of the hanging body (3) is measured by the photoelectric gate speed measuring device. The hanging body (3) comprises a cylinder (13) and a cylindrical body (14); the cylinder (13) is a thin-walled metal cylinder, and the inside is connected with the metal cylindrical body (14) through a spiral; the upper surface center of the cylindrical body (14) is connected with the thin rope (4), and the lower bottom surface and the side surface are connected with the circular arc surface. The hanging body (3) falls in the long tube (2) filled with liquid; the forces acting on the hanging body (3) include: (1) the combined force F1 of the external upward pulling force, which includes the gravity of the weight (8) and the friction resistance of the rotation of the fixed pulley (7), and the direction is upward; (2) the combined force F2 of the viscous resistance generated in the liquid, the buoyancy of the hanging body (3) in the liquid and the movement resistance of the annular orifice formed by the hanging body (3) and the inner wall of the long tube (2), and the direction is upward; (3) the gravity F of the hanging body (3) itself, and the direction is downward; when F>F1+F2, the hanging body (3) falls in the liquid with acceleration; when F1+F2=F, the hanging body (3) starts to fall at a constant speed; if the falling speed of the hanging body (3) is too fast or too slow, the falling speed of the hanging body (3) can be adjusted by changing the structure of the hanging body (3) itself, that is, the cylindrical body (14) is rotated downward to extend out of the cylinder (13), the throttling length of the annular orifice is increased, the falling speed of the hanging body (3) is reduced, and vice versa, the cylindrical body (14) is rotated upward to retract into the cylinder (13), the length of the annular orifice is reduced, and the falling speed of the hanging body (3) is increased, so that the constant speed of the hanging body (3) meets the requirements of observation and measurement.

2. The Newton's First Law Apparatus of claim 1, wherein, The photoelectric gate speed measuring device comprises an A photoelectric gate (9), a stand (10), a B photoelectric gate (11) and a moving seat (12). The mobile seat (12) is a metal disc, which can be placed on the base (1) to move, the center of the mobile seat (12) is vertically upward fixed with a stand (10), the stand (10) is marked with a scale, the stand (10) is sequentially installed with an A photoelectric gate (9) and a B photoelectric gate (11) from top to bottom, each photoelectric gate can freely move on the stand (10), and the distance between the two photoelectric gates can be read through the scale; The A photoelectric gate (9) and the B photoelectric gate (11) are placed outside the long tube (2) during measurement, and are connected with a timing device.

3. The Newton's First Law Apparatus of claim 1, wherein, The inner recess of the fixed pulley (7) is vertically aligned with the center of the circular hole (6) on the cover (5), so that when the suspension body (3) falls into the bottom of the long tube (2), the thin rope (4) coincides with the axis of the long tube (2) and does not contact the circular hole (6) on the cover (5).

4. The Newton's First Law Apparatus of claim 1, wherein, The suspension body (3) passes through the light emitting device and the receiving device between the two photoelectric gates in the long tube (2), and the suspension body (3) can block the light emitted by the light emitting device.

5. The Newton's First Law laboratory apparatus of claim 1, wherein, The liquid medium in the long tube (2) is a transparent liquid.

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