Theme. Laboratory work№ 1 "Determination of body acceleration in case of equal accelerated motion"
Lesson goal: measure the acceleration of a ball rolling down an inclined chute
Lesson type: control and assessment of knowledge
Equipment: metal chute, tripod with clutch and clamp, steel cylinder, measuring tape, stopwatch or watch with second hand
PROGRESS
1. Assemble the installation shown in the figure (the top end of the gutter should be a few centimeters higher than the bottom). Place a metal cylinder on the lower end of the groove. When the ball rolls down and hits the cylinder, the impact sound will help you more accurately determine the time the ball is moving.
2. Mark the start position of the ball on the groove, as well as its end position - the top end of the metal cylinder.
3. Measure the distance between the upper and lower marks on the groove (the path traveled by the ball) and record the measurement in the table.
4. Having fixed the moment when the second hand is at a division that is a multiple of 10, release the ball without pushing at the upper mark and measure the time t before the ball hits the cylinder.
Repeat the experiment three times, writing down the measurement results in the table. During each experiment, launch the ball from the same starting position, and also make sure that the upper end of the cylinder is at the appropriate division.
l, m |
t, s |
t sir, c |
||
5. Calculate 
and write down the result in the table.
6. Calculate the acceleration with which the ball rolled: Record the result of the calculations in the table.
7. To calculate the error, use the method of estimating the error of indirect measurements and find the limits amax and min, in which there is true meaning acceleration:
8. Calculate the average value a sir and the absolute measurement error Yes using the formulas:
9. Calculate the relative measurement error:
10. Record the calculation results in the table:
smax |
smin |
tmin |
tmax |
amax |
amin |
acep |
||
11. Write down in a notebook for laboratory work the result in the form a = asp ± ∆ a, substituting the numerical values of the calculated values into the formula.
12. Write down the conclusion in a notebook for laboratory work: what you measured and what result you got.
Laboratory work No. 2 in physics grade 9 (answers) - Determination of acceleration at uniformly accelerated motion body
5. Find and enter the average values into the table
6. Calculate and enter into the table the average value of the acceleration of the ball according to the formula.
7. Calculate and enter into the table the value absolute errorΔl.
8. Calculate the maximum value of the absolute random error in measuring the time interval t.
9. Determine the absolute systematic error of the time interval t.
10. Calculate the value of the absolute error of direct measurement of the time interval t.
11. Calculate the values relative error measuring length and time span.
| l | t | a | Δl | Δt | ε | ε | |
| 1 | 65 | 1,43 | - | 0,1 | 0,48 | 0,15 | 29,81 |
| 2 | 65 | 1,8 | - | - | - | - | - |
| 3 | 65 | 1,38 | - | - | - | - | - |
| 4 | 65 | 1,71 | - | - | - | - | - |
| 5 | 65 | 1,72 | - | - | - | - | - |
| Wed | 65 | 1,61 | 50,19 | - | - | - | - |
Answer security questions
1. What is the modulus of movement for a given motion of the ball? how is the displacement vector directed?
Represents a vector that connects two points of a motion path, a start point and an end point. The vector in this case is the gutter.
2. Will the average speed of the ball be equal when it moves on the first and second half of the path? Why?
Average speeds will be different, because during movement on the ball there are forces of gravity and friction, which are able to slow it down.
Conclusions: I learned how to calculate the acceleration of a rolling ball and the errors in measuring the time of movement of the ball along the chute.
Outline of a physics lesson in grade 9
Theme: Laboratory work No. 1 "Measuring the acceleration of a body with uniformly accelerated motion."
Physics teacher, KSU "Secondary School No. 13": Ganovicheva M. A.
Educational learn to measure acceleration at uniformly accelerated straight motion; to experimentally establish the ratio of the paths traversed by the body during uniformly accelerated rectilinear motion for successive equal intervals of the body.
Developmental: promote the development of speech, thinking, cognitive and general educational skills: plan actions, cook workplace, draw up the results of work; to promote the mastery of the methods of scientific research: analysis and synthesis.
Educational: to form a conscientious attitude towards educational work, positive motivation for learning, communication skills; contribute to the education of humanity, discipline.
Lesson type: Lesson to consolidate theoretical knowledge.
Form of implementation: Research work.
Lesson plan:
I. Organizational stage.
2. The stage of updating basic knowledge.
3. Stage of independent work of students.
4. Reflection.
5. The final stage.
Material support for each group:report form; instruction cut into phrases;
laboratory metal gutter 1.4 m long, metal ball 1.5-2 cm in diameter, metronome, ruler.
During the classes:
Organizing moment.
Greetings. Establishing work discipline. Absent mark. Communication of goals and lesson plan. Dividing the class into groups by random selection.
Because today you work in groups, everyone should try to do their part as well as possible. Let's check the d / z. Each group member answers the questions after paragraph 5 to his peers.
Let's talk about TB. To prevent accidents, devices on the demonstration table should be placed in such a way as to exclude any possibility of flying parts falling into students during experiments.
Before starting the work, understand the progress by listening to the teacher.
For the emergence of a dialogue, students are offered instructions for performing laboratory work, cut into phrases Appendix 2. This required students not just to reproduce previously acquired knowledge, but to reveal logic scientific research.
Pupils were asked to discuss a practical task, outline ways to solve it, put them into practice and, finally, present the result found jointly.
That implied the development of the ability to clearly express one's thoughts (build complete and clear statements) and understand a partner (listen to him, grasp not only the direct meaning of his phrases, but also their meaning).
Glue the instructions, fill in the blank lines and columns.
DURING WORK
1. Be attentive, disciplined, careful.
2. Do not leave the workplace without the teacher's permission.
3. Arrange devices, materials, equipment in the workplace in order, there should be no foreign objects on the table. Handle the metal ball with care! Do not tighten the tripod couplings too much!
If you find any malfunctions in the condition of the devices you are using, notify the teacher
Students perform laboratory work, draw conclusions on it, fill out a report form Annex 1. If the students are familiar with the logic of scientific research, then they will glue the instructions in the order below.
PROGRESS:
Assemble the installation according to the picture
Release the ball from the top end of the chute
Measure the distance h - the height of the upper end of the chute and the distance S traveled by the ball.
Calculate the time t the ball moves, based on the number of beats of the metronome.
Calculate the acceleration of the ball
Change the slope of the gutter, repeat the experiment two more times.
Enter the results of measurements and calculations in the table.
Distance, S, m | The number of beats of the metronome | Travel time t = 0.5 n, | Acceleration, a = 2 S / t2, m / s 2 | ||
Calculate the average acceleration.
Write down the conclusion: what you measured and what the result was.
The teacher conducts consulting individual work and accepts the report and answers to control questions from the first group that completed it. These students then act as teachers and receive reports from the following groups.
4. Reflection.
Well, our lesson is coming to an end. In the atmosphere and environment in which we worked today, each of you felt differently. And now I would like you to appreciate how internally you felt comfortable in this lesson, each of you, all together as a class, and whether you liked the business that we were doing today.
5. The final stage.
Now let's evaluate your work together in today's lesson. Groups and grades are named. Each of you was in the group during the lesson and the mark received today is given the same to each member of the group. Let's define the groups for the next lesson. You have to carry out an experiment that Galileo did many times to determine the acceleration of falling objects. The groups are given an early task: to find information about Galileo, assign roles and plan the group's work.
Annex 1
Laboratory report No. 1
Measuring the acceleration of a body with uniformly accelerated motion
Groups 9 "__" ___________________________________________________________________________________________________________
Purpose of work: to measure the acceleration of a ball rolling down an inclined chute.
Equipment: metronome, ________________________________________________________________________________________________________________
Appendix 2
PROGRESS:
Assembled the installation according to the picture
Loose the ball from the top end of the chute
The distance S traveled by the ball was measured.
We calculated the time t of the ball's movement, according to the number of beats of the metronome.
Calculated the acceleration of the ball
The slope angle of the gutter was increased, and the experiment was repeated.
The results of measurements and calculations were entered into a table.
Distance, S, m | Height of the upper end of the gutter, m | The number of beats of the metronome | Travel time t = 0.5 n, | Acceleration, a = 2 S / t2, m / s 2 | |
Calculated the average acceleration.
Output:
Physics for grade 9 (I.K. Kikoin, A.K. Kikoin, 1999),
task №1
to chapter " LABORATORY WORKS».
Purpose of work: to calculate the acceleration with which the ball rolls along the inclined chute. To do this, measure the length of movement s of the ball for known time t. Since at uniformly accelerated motion without initial speed
then, by measuring s and t, you can find the acceleration of the ball. It is equal to:
No measurements are taken with absolute precision. They are always produced with some error associated with imperfection of measuring instruments and other reasons. But even in the presence of errors, there are several ways to make reliable measurements. The simplest of them is the calculation of the arithmetic mean from the results of several independent measurements of the same quantity, if the conditions of the experiment do not change. This is what it is proposed to do in the work.
Measuring instruments: 1) measuring tape; 2) metronome.
Materials: 1) gutter; 2) a ball; 3) a tripod with couplings and a foot; 4) metal cylinder.
Work order
1. Secure the chute with a tripod in an inclined position at a slight angle to the horizon (fig. 175). Place a metal cylinder in the bottom end of the gutter.
2. With the ball running (along with the metronome beat) from the top end of the chute, count the number of beats of the metronome until the ball hits the cylinder. It is convenient to carry out the experiment at 120 metronome beats per minute.
3. Changing the angle of inclination of the chute to the horizon and making small movements of the metal cylinder, ensure that between the moment the ball is launched and the moment it collides with the cylinder, there are 4 metronome beats (3 intervals between beats).
4. Calculate the time the ball moves.
5. Using a tape measure, determine the travel length s of the ball. Without changing the slope of the chute (the conditions of the experiment must remain unchanged), repeat the experiment five times, achieving again the coincidence of the fourth beat of the metronome with the impact of the ball on the metal cylinder (the cylinder can be moved a little for this).
6. According to the formula
find the average of the displacement modulus and then calculate the average of the acceleration modulus:
7. Enter the results of measurements and calculations in the table:
|
mean |
Calculations:
Calculation of errors
The task:
Problem number 1
Purpose of work: to calculate the acceleration with which the ball rolls along the inclined chute. To do this, measure the length of movement s of the ball for a known time t. Since at uniformly accelerated motion without initial speed
then, by measuring s and t, you can find the acceleration of the ball. It is equal to: 
No measurements are taken with absolute precision. They are always produced with some error associated with imperfection of measuring instruments and other reasons. But even in the presence of errors, there are several ways to make reliable measurements. The simplest of them is the calculation of the arithmetic mean from the results of several independent measurements of the same quantity, if the conditions of the experiment do not change. This is what it is proposed to do in the work.
Measuring instruments: 1) measuring tape; 2) metronome.
Materials: 1) gutter; 2) a ball; 3) a tripod with couplings and a foot; 4) metal cylinder.
Work order
1. Secure the chute with a tripod in an inclined position at a slight angle to the horizon (fig. 175). Place a metal cylinder in the bottom end of the gutter. 
2. With the ball running (along with the metronome beat) from the top end of the chute, count the number of beats of the metronome until the ball hits the cylinder. It is convenient to carry out the experiment at 120 metronome beats per minute.
3. Changing the angle of inclination of the chute to the horizon and making small movements of the metal cylinder, ensure that between the moment the ball is launched and the moment it collides with the cylinder, there are 4 metronome beats (3 intervals between beats).
4. Calculate the time the ball moves.
5. Using a tape measure, determine the travel length s of the ball. Without changing the slope of the chute (the conditions of the experiment must remain unchanged), repeat the experiment five times, achieving again the coincidence of the fourth beat of the metronome with the impact of the ball on the metal cylinder (the cylinder can be moved a little for this).
6. According to the formula 
find the average of the displacement modulus and then calculate the average of the acceleration modulus: 
7. Enter the results of measurements and calculations in the table:
Experience number
Number
blows
underground
noma
arr, m / s2
With rectilinear uniformly accelerated motion without initial speed 
where S is the path traversed by the body, t is the travel time. Measuring tools: measuring tape (ruler), metronome (stopwatch).
The laboratory setup and the procedure for performing the work are described in detail in the tutorial.
mean
Calculations: 
Calculation of errors
Instrument accuracy: Measuring tape: 
Stopwatch: 
Let's calculate the absolute errors: 
Let's calculate the relative error: 
Indirect measurement absolute error:
The acceleration found as a result of the work can be written as follows:
but for a given absolute error, the last digit in the value of asp does not matter, so we write it like this: