Фізика 7 НУШ. Лаб. №1 в 3d: Визначення середньої швидкості руху тіла (Урок №15, 3D симулятор) — Transcript

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1. 0:02Lesson 15. Laboratory work number one.
2. 0:07Determining the average speed of a body
3. 0:09. 3D version. The goal is to study
4. 0:18non-uniform motion of a body. To learn
5. 0:22how to determine the average speed of a
6. 0:23body. Equipment: PC or smartphone and
7. 0:28an interactive 3D simulator. Virtual
8. 0:34equipment: stopwatch, chute, tripod,
9. 0:37ball, ruler, metal cylinder. In this
10. 0:52lab work, the average speed of a body
11. 0:54is determined experimentally: by using
12. 0:56a tape or ruler, the distance traveled
13. 0:58by the ball in a certain time interval
14. 1:01as it moves down an inclined chute is
15. 1:03measured. Using the obtained
16. 1:13experimental data and the average speed
17. 1:15formula (V average equals distance L
18. 1:18divided by time T), the target value is
19. 1:20calculated. Finally, the average speeds
20. 1:28for each trial are compared, and the
21. 1:30reasons for any discrepancies in their
22. 1:32values are determined. The typical
23. 1:37procedure is as follows. First, secure
24. 1:42the chute at an angle to the table
25. 1:44surface. Measure the distance L (small)
26. 1:49from the ball to the metal cylinder.
27. 1:53Third. Measure the time T (small) for
28. 1:56the ball to roll down. Fourth. Repeat
29. 2:01the experiment two more times. Each
30. 2:05time reducing the distance to the
31. 2:07cylinder. Fifth. For each trial,
32. 2:14determine the average speed of the ball
33. 2:16. Enter the obtained data into the
34. 2:22table shown on the screen. During the
35. 2:26experiment, it is necessary to follow
36. 2:28safety rules and strictly adhere to the
37. 2:30instructions. You can learn more about
38. 2:34the real experiment from the video
39. 2:36lesson on our channel using the link on
40. 2:38the screen. If it is not possible to
41. 2:47assemble the recommended experimental
42. 2:49setup, this lab work can also be
43. 2:51performed using an interactive 3D
44. 2:53simulator, which is available on a PC,
45. 2:55tablet, or smartphone via the link you
46. 2:58will easily find in the video
47. 2:59description. The application was
48. 3:04developed in accordance with the
49. 3:06requirements of the lab work. So, first
50. 3:09. Open the interactive application
51. 3:12using the link; second. Record the
52. 3:17initial distance L (small) from the
53. 3:19ball to the metal cylinder. Measure the
54. 3:23time T (small) for the ball to roll
55. 3:25down; fourth. Repeat the experiment two
56. 3:28more times. Each time reducing the
57. 3:32distance to the cylinder. Be sure to
58. 3:38enter the obtained data into the table.
59. 3:42But before you start the experiment, it
60. 3:44is worth watching the video to the end
61. 3:46and taking note of the following tips
62. 3:48when using the simulator. The
63. 3:55interactive simulator for the lab work
64. 3:57on determining average speed is
65. 3:59controlled with a mouse as follows. If
66. 4:05we hold down the left mouse button, the
67. 4:07camera rotates around our virtual setup
68. 4:10. If we hold down the right mouse
69. 4:15button, the camera can be moved up and
70. 4:17down, left and right. If we scroll the
71. 4:22wheel, we zoom out or in on the scene.
72. 4:28For example, if we need to see at which
73. 4:30mark our ball is located, in what
74. 4:32position, we zoom in and clearly
75. 4:34determine the position on the ruler
76. 4:36marked on the chute. For example, right
77. 4:41now the edge of the ball aligns with
78. 4:43the value 187. cm. This is the position
79. 4:50of the ball at the beginning when our
80. 4:52scene loads. This is the maximum
81. 5:01distance the ball can travel along the
82. 5:03inclined chute until it hits the
83. 5:05cylinder, which is located at the
84. 5:06bottom, and its position is at the zero
85. 5:09mark of our ruler. Thus, our
86. 5:18experimental setup is now practically
87. 5:20ready. It is already prepared. And we
88. 5:26can begin our first experiment, where
89. 5:29the ball travels down an inclined chute
90. 5:31at a certain angle, in this case, 33 °
91. 5:34. This is clearly visible on the
92. 5:39control panel. It will roll down and
93. 5:45travel a distance of 187 cm or 1.87 m.
94. 6:00If we divide the number in centimeters
95. 6:02by 100, to start the experiment—that
96. 6:05is, to set the ball in motion and begin
97. 6:07timing its travel—we need to press
98. 6:09the start button on mobile phones so
99. 6:11that the control panel does not obscure
100. 6:13the scene. This is best done using the
101. 6:26button next to the control menu, into
102. 6:28which the control panel collapses. When
103. 6:34pressed, this button allows us to
104. 6:36release the ball and start the
105. 6:37stopwatch sitting on the table. We can
106. 6:44record the moment the motion ends in
107. 6:46two ways: by directly watching the ball
108. 6:48at the moment of impact. Or, if your
109. 6:55browser version is up to date and has
110. 6:57no restrictions, by listening to the
111. 6:59sound of the impact. Therefore, if
112. 7:05possible, increase the volume on your
113. 7:08computer or smartphone and begin the
114. 7:10experiment. The stopwatch must be
115. 7:16stopped manually, just as it is done in
116. 7:18a real, live experiment. So, let's
117. 7:23begin. We press start and stop. As we
118. 7:29can see, the ball traveled a distance
119. 7:32of 1 m 87 cm or 187 cm in 1.68 seconds.
120. 7:49If everything was done well, and you
121. 7:51believe you did not mistime the
122. 7:53pressing of the stop button, these data
123. 7:55can now be entered into the table. If
124. 8:04you made a mistake, you can reset the
125. 8:06stopwatch, return the ball to its
126. 8:08starting position, and repeat the
127. 8:09experiment. Now we have measured a
128. 8:18value of 1.64 seconds at the same
129. 8:24distance of 187 cm. These L and T
130. 8:29values can, I repeat, be entered into
131. 8:35our table for experiment one. To move
132. 8:41the ball to a specific position, you
133. 8:44must first—this is a mandatory
134. 8:46requirement—reset the stopwatch to
135. 8:48avoid confusing the data. Then we will
136. 8:53have the ability to change the position
137. 8:55of the ball. The next two experiments
138. 9:06should be performed at distances
139. 9:07smaller than the maximum. And
140. 9:15accordingly, they will need to be
141. 9:16measured. The ball's position can be
142. 9:20set either with a mouse or a finger on
143. 9:23a smartphone touchscreen, or by using
144. 9:25the slider. Ball position. Moreover,
145. 9:29the slider moves the ball in increments
146. 9:32of 1 cm. While moving it with a finger
147. 9:38on a smartphone or a mouse on the scene
148. 9:40, the movement will be performed with a
149. 9:42precision of 1 mm. Therefore, for
150. 9:48easier positioning of the ball, it
151. 9:50might be better to use the slider. To
152. 9:55lock the position, we need to approach
153. 9:57the scene without having our hand in
154. 9:59the way, otherwise, we will grab the
155. 10:01ball. We are interested in the value of
156. 10:06the final position of our ball. In this
157. 10:10case, we are talking about 136 cm. The
158. 10:17ball is not a point mass, so we need to
159. 10:19track one of the points on the surface
160. 10:21of the ball and the path it travels.
161. 10:28Since the ball, at the moment it
162. 10:30touches the cylinder, will have its
163. 10:32edge at the zero mark. Therefore, it is
164. 10:40best for us to orient ourselves when
165. 10:42setting distance L to its extreme right
166. 10:44side. That is, we now have a value of
167. 10:52136 cm. This value can be entered into
168. 10:59the table, provided that we conduct the
169. 11:01experiment well and measure the time.
170. 11:07Let's do that as well. So, in this way,
171. 11:11let's observe how the ball moves. We
172. 11:14press start and stop once more. After
173. 11:19this, we also enter these data,
174. 11:21distance and time, into the table. Next
175. 11:27, we need to choose a third trial again
176. 11:29at an even shorter distance and repeat
177. 11:31the experiment. Determining the
178. 11:38distance and measuring the time it
179. 11:40takes for the ball to cover it, hitting
180. 11:42the cylinder at the end of its movement
181. 11:44. Fifth. For each trial, determine the
182. 11:56average speed of the ball using the
183. 11:58formula: V average equals L small.
184. 12:04Distance divided by the time of the
185. 12:06ball's movement, T small. For example,
186. 12:12for trial one that we conducted, we
187. 12:15have that dividing 1.87 meters by 1.64
188. 12:26seconds will give us an average speed
189. 12:28of the ball of 1.14 meters per second.
190. 12:36Note that the experiment in the
191. 12:37simulator is accompanied by an
192. 12:39invisible assistant who records the
193. 12:41data simultaneously with you in real
194. 12:43time on the board in the form of a
195. 12:45physics problem solution. This allows
196. 12:47for a better understanding, through an
197. 12:49example, of how the calculation process
198. 12:52takes place. However, the numerical
199. 12:54value itself will have to be calculated
200. 12:57on your own. Also, the assistant will
201. 13:02not help at all in trials two and three
202. 13:04on the shorter paths of the ball. The
203. 13:11last thing to pay attention to is that
204. 13:13the simulator loads with a different
205. 13:15trough length and tilt angle each time,
206. 13:17so all three trials should be completed
207. 13:19without reloading the page with the
208. 13:21interactive application during the
209. 13:23experiment. Based on the results of the
210. 13:34experiment, formulate a conclusion in
211. 13:36which you state: first, what movement
212. 13:38you studied; second, the value of which
213. 13:41quantity you determined. Third, record
214. 13:47the results of the experiment that you
215. 13:49obtained. Fourth. Compare the average
216. 13:54speeds of each experiment and explain
217. 13:56why these values do not coincide. And
218. 14:00fifth, what factors influenced the
219. 14:02accuracy of the experiment. Control
220. 14:08tasks. First. The figure shows a graph
221. 14:12of the body's speed versus time.
222. 14:15Explain the nature of the body's
223. 14:17movement. Second. During the movement
224. 14:21of a car, speedometer readings were
225. 14:23recorded every minute. Is it possible
226. 14:26to determine the average speed of the
227. 14:28car from these data? Third. One body
228. 14:35covers a distance of 120 km at a speed
229. 14:38of 40 km/h, and in the opposite
230. 14:41direction at a speed of 30 km/h.
231. 14:46Another body covers the same distance
232. 14:49in both directions with an average
233. 14:51speed of 40 km/h. Do both bodies spend
234. 14:56the same amount of time on the round
235. 14:58trip? Creative task. Conduct the
236. 15:07experiment according to the same plan,
237. 15:09changing the angle of the trough and
238. 15:11switching the ball from plastic to
239. 15:13metal or vice versa. Do these factors
240. 15:17affect the ball's average speed, and if
241. 15:20so, how? Additionally, the laboratory
242. 15:28simulator for determining an object's
243. 15:30average speed allows you to experiment
244. 15:32with different balls: metal, glass,
245. 15:35plastic, or wood. The balls are the
246. 15:43same size, but because the materials
247. 15:45differ, their density and mass are also
248. 15:47different. If we look at the ruler, the
249. 15:54size of the ball we are experimenting
250. 15:56with is slightly smaller than a tennis
251. 15:58ball. Therefore, a metal ball of this
252. 16:05size will weigh about 1 kg, or to be
253. 16:08precise, 882 grams in our case, while
254. 16:11the plastic one, for example, is only
255. 16:14136. Thus, we can experiment with
256. 16:21different balls by launching them from
257. 16:23the maximum height, glass, plastic,
258. 16:31wooden, and determine what the average
259. 16:33speed will be over a given section of
260. 16:35the path. Likewise, you can experiment
261. 16:40with a specific ball, for example, the
262. 16:43same metal one, by changing the angle
263. 16:45of inclination for the trough. And
264. 16:52again, following the same scenario, by
265. 16:54determining the average speed for the
266. 17:03very same distance, the same path that
267. 17:05the ball travels, but for different
268. 17:07angles of the trough relative to the
269. 17:09table. Homework assignment: review
270. 17:18paragraph 11.