Conclusion laboratory work study of the law of conservation of mechanical energy. Studying the law of conservation of mechanical energy Laboratory work 5 studying the law of conservation of energy

Lab #13

Study of the law of conservation of mechanical energy

Laboratory work "Studying the law of conservation of mechanical energy"

Laboratory work No. 7 "Studying the law of conservation of mechanical energy"

Course of laboratory work 5. Studying the law of conservation of mechanical energy

home › Love and relationships › Conclusion laboratory work study of the law of conservation of mechanical energy. Studying the law of conservation of mechanical energy Laboratory work 5 studying the law of conservation of energy

Ufa State Aviation Technical University

(in physics)

Faculty: IRT

Group: T28-120

Completed by: Dymov V.V.

Checked:

1. The purpose of the work: The study of the law of conservation of mechanical energy and verification of its validity using Maxwell's pendulum.

2. Devices and accessories: Maxwell's pendulum.

Base

Adjustable feet

Column, mm scale

Fixed bottom bracket

Movable arm

Electromagnet

Photoelectric sensor #1

Knob for adjusting the length of the bifilar suspension of the pendulum

Photoelectric sensor #2

Replacement rings
Millisecond watch

3. Table with the results of measurements and calculations

3.1 Measurement results

t, sec

m, kg

h max , m

t cp , With

J, kg*m 2

a, m/s 2

t 1 =2,185

t 2 =3,163

t 3 =2,167

m d =0,124

m about =0,033

m to =0,258

h max =0,4025

t Wed =2,1717

t Wed =2.171±0.008

J=7.368*10 -4

a= 0,1707

a=0.1707±0.001

3.2 Experimental results

№ experience	t, sec	h, m	E n , J	E n , J	E k , J	E k , J
	t’=1,55	h’=0,205	E n ’=0,8337	E n ’=2,813810* -2	E k ’= 1,288
	t’’= 0	h’’=0,4025	E n ’’= 2,121 6		E k ’’= 0
	t’ ’ ’=2,1717	h’ ’ ’=0	E n ’’’=0		E k ’’ ’ = 2,12 19

4. Calculation of measurement results and errors

4.1. Direct measurement of the time of full fall of the pendulum

t 1 =2.185c.

t 2 =3.163c.

t 3 =2.167c.

4.2. Average total fall time calculation

4.3. Calculation of the acceleration of the translational motion of the pendulum

l\u003d 0.465m - thread length

R=0.0525m– ring radius

h= l- R-0.01m=0.4025m- the path when the pendulum falls

4.4. Calculation of the height of the pendulum at the moment of time t’

;

;
;

v’ is the speed of translational motion at a moment of time t’

- the speed of the rotational movement of the pendulum axis at the moment of time t’

r=0.0045m is the radius of the pendulum axis

4.5. Calculating the moment of inertia of a pendulum

J 0 – moment of inertia of the pendulum axis

m 0 =0.033kg – pendulum axle weight

D 0 =
– axle diameter pendulum

J d – disk moment of inertia

m d =0.124kg – disk mass

D d =
– disc diameter

J to – moment of inertia of the trim ring

m to =0.258kg – trim ring weight

D to =0.11m - trim ring diameter

4.6. Calculation of the potential energy of a pendulum with respect to an axis passing along the axis

pendulum, at a position at a time t’

4.7. Calculation of the kinetic energy of the pendulum at a moment in time t’

-kinetic energy of translational motion

-kinetic energy of rotational motion

4.8. Calculation of the error of direct measurements

4.9. Calculation of errors of indirect measurements

5. End results:

The total mechanical energy of the pendulum at some point in time is equal to E= E n + E k

For experience #1: E’= E n ’+ E k '=0.8337J+1.288J=2.1217J

For experience #2: E’’= E n ’’+ E k ''=2.1216J+0=2.1216J

For experience #3: E’’’= E n ’’’+ E k '''=0+2.1219J=2.1219J

It follows from these experiments that
(difference in 10 -3 J due to the imperfection of measuring instruments), therefore, the law of conservation of total mechanical energy is correct.

Selected document to view Lab 2.docx

MBOU secondary school r.p. Lazarev Nikolaev district Khabarovsk Territory
Completed by: physics teacher T.A. Knyazeva

Laboratory work №2. Grade 10

Study of the law of conservation of mechanical energy.

Objective: learn how to measure the potential energy of a body raised above the ground and an elastically deformed spring, compare two values of the potential energy of the system.

Equipment: a tripod with a clutch and a foot, a laboratory dynamometer with a lock, a measuring tape, a weight on a thread about 25 cm long.

We determine the weight of the ball F 1 \u003d 1 N.

The distance l from the hook of the dynamometer to the center of gravity of the ball is 40 cm.

The maximum elongation of the spring l \u003d 5 cm.

Force F \u003d 20 N, F / 2 \u003d 10 N.

Fall height h = l + l =40+5=45cm=0.45m.

E p1 \u003d F 1 x (l + l) \u003d 1Hx0.45m \u003d 0.45J.

E p2 \u003d F / 2x L \u003d 10Nx0.05m \u003d 0.5J.

The results of measurements and calculations will be entered in the table:

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STUDY OF THE LAW OF CONSERVATION OF MECHANICAL ENERGY

Objective: experimentally establish that the total mechanical energy of a closed system remains unchanged if only gravitational and elastic forces act between the bodies.

Equipment: a device for demonstrating the independence of the action of forces; scales, weights, measuring ruler; plumb; white and carbon paper; tripod for front work.

The setup for the experiment is shown in the figure. When the rod A deviates from the vertical position, the ball at its end rises to a certain height h relative to the initial level. In this case, the system of interacting bodies "Earth-ball" acquires an additional supply of potential energy ? E p = mgh .

If the rod is released, it will return to the vertical position, where it will be stopped by a special stop. Considering the friction force to be very small, it can be assumed that during the movement of the rod, only gravitational and elastic forces act on the ball. Based on the law of conservation of mechanical energy, it can be expected that the kinetic energy of the ball at the moment of passing the initial position will be equal to the change in its potential energy:

By calculating the kinetic energy of the ball and the change in its potential energy, and comparing the results obtained, it is possible to experimentally verify the law of conservation of mechanical energy. To calculate the change in the potential energy of the ball, you need to determine its mass m on the scales and measure the height h of the ball's rise using a ruler.

To determine the kinetic energy of a ball, it is necessary to measure the modulus of its velocity?. To do this, the device is fixed above the table surface, the rod with the ball is moved to the side to the height H + h and then released. When the rod hits the stop, the ball jumps off the rod.

The speed of the ball during the fall changes, but the horizontal component of the speed remains unchanged and equal in absolute value to the speed? ball at the moment of impact of the rod on the stop. So speed? ball at the moment of falling off the rod can be determined from the expression

V \u003d l / t, where l is the range of the ball, t is the time of its fall.

The time t of free fall from a height H (see Fig. 1) is equal to: , therefore

V \u003d l / v 2H / g. Knowing the mass of the ball, you can find its kinetic energy: E k \u003d mv 2 / 2 and compare it with potential energy.

Work order

1. Fix the device in a tripod at a height of 20-30 cm above the table, as shown in the figure. Put the ball with the hole on the rod and make a preliminary experiment. At the crash site
ball, tape a sheet of white paper and cover it with a sheet of carbon paper.

3. Putting the ball back on the rod, move the rod to the side, measure the height of the ball h in relation to the initial level and release the rod. Having removed a sheet of carbon paper, determine the distance l between the point on the table under the ball in its initial position, found by the plumb line, and the mark on the sheet of paper at the point where the ball fell.

4. Measure the height of the ball above the table in the starting position. Weigh the ball and calculate the change in its potential energy? E p and kinetic energy Ek at the moment the ball passes through the equilibrium position.

5. Repeat the experiment for the other two heights h and make measurements and calculations. Record the results in a table.

7. Compare the values of changes in the potential energy of the ball with its kinetic energy and draw a conclusion about the results of your experiment

Reshebnik in physics for grade 9 (I.K. Kikoin, A.K. Kikoin, 1999),
a task №7
to chapter " LABORATORY WORKS».

measuring; 3) cargo from the mechanics kit; the weight of the load is (0.100 ±0.002) kg.

Materials: 1) retainer;

2) a tripod with a clutch and foot.

and the energy of the spring when it is deformed increases by

Work order

LABORATORY WORKS> number 7

The purpose of the work: to compare two quantities - a decrease in the potential energy of a body attached to a spring when it falls and an increase in the potential energy of a stretched spring.

1) a dynamometer with a spring stiffness of 40 N/m; 2) ruler

Measuring; 3) cargo from the mechanics kit; the weight of the load is (0.100 ±0.002) kg.

Materials: 1) retainer;

2) a tripod with a clutch and foot.

For work, the installation shown in Figure 180 is used. It is a dynamometer mounted on a tripod with lock 1.

The dynamometer spring ends with a wire rod with a hook. The latch (on an enlarged scale it is shown separately - marked with the number 2) is a light cork plate (5 X 7 X 1.5 mm in size), cut with a knife to its center. It is mounted on the wire rod of the dynamometer. The retainer should move along the rod with little friction, but the friction must still be sufficient so that the retainer does not fall down on its own. You need to make sure of this before starting work. To do this, the latch is installed at the lower edge of the scale on the restrictive bracket. Then stretch and release.

The latch together with the wire rod should rise up, marking the maximum elongation of the spring, equal to the distance from the stop to the latch.

If we raise the load hanging on the hook of the dynamometer so that the spring is not stretched, then the potential energy of the load with respect to, for example, the surface of the table is equal to mgH. When the load falls (lowering to a distance x = h), the potential energy of the load will decrease by

And the energy of the spring when it is deformed increases by

Work order

1. Attach the weight from the mechanics kit firmly to the hook of the dynamometer.

2. Raise the load by hand, unloading the spring, and install the latch at the bottom of the bracket.

3. Release the load. As the weight falls, it stretches the spring. Remove the load and, by the position of the latch, measure the maximum elongation x of the spring with a ruler.

4. Repeat the experiment five times.

6. Enter the results in the table:

7. Compare the ratio

With unity and draw a conclusion about the error with which the law of conservation of energy was tested.

The law of conservation of mechanical energy. The total mechanical energy of a closed system of bodies interacting with gravitational forces or elastic forces remains unchanged during any movements of the bodies of the system

Consider such a body (in our case, a lever). Two forces act on it: the weight of the loads P and the force F (the elasticity of the spring of the dynamometer), so that the lever is in balance and the moments of these forces must be equal in absolute value to each other. The absolute values of the moments of forces F and P will be determined respectively:

Consider a weight attached to an elastic spring in such a way as shown in the figure. First, we hold the body in position 1, the spring is not stretched and the elastic force acting on the body is zero. Then we release the body and it falls under the action of gravity to position 2, in which the gravity force is fully compensated by the elastic force of the spring when it is extended by h (the body is at rest at this moment in time).

Consider the change in the potential energy of the system when the body moves from position 1 to position 2. When moving from position 1 to position 2, the potential energy of the body decreases by mgh, and the potential energy of the spring increases by

The purpose of this work is to compare these two quantities. Measuring instruments: a dynamometer with a spring stiffness of 40 N/m known in advance, a ruler, a weight from the mechanics set.

F t =mg

h = l + ∆l

E" P = mg (l + ∆l)

E" P = F ex ∆l/2

1. Assemble the installation shown in the figure.

2. Tie a load on the thread to the hook of the dynamometer (thread length 12-15 cm). Fix the dynamometer in the tripod clamp at such a height that the weight lifted up to the hook, when dropped, does not reach the table.

3. After lifting the weight so that the thread sags, install the clamp on the dynamometer rod near the limit bracket.

4. Raise the load almost to the dynamometer hook and measure the height of the load above the table (it is convenient to measure the height at which the lower edge of the load is located).

9. Compare the resulting ratio with the unit and write down the conclusion in the notebook for laboratory work; indicate what transformations of energy occurred when the load moved down.

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Autonomous institution

vocational education

Khanty-Mansiysk Autonomous Okrug - Yugra

"SURGUT POLYTECHNICAL COLLEGE"

Kuzmaul Maria Sergeevna, teacher of physics

Lesson topic: Laboratory work No. 3 " Study of the law of conservation of mechanical energy.

Lesson type: laboratory-practical

Receptions: "Logbook", explanatory and illustrative, algorithmization.

The purpose of the lesson: study the law of conservation of energy in the course of practical work

Lesson objectives:

Educational:

teach how to use instruments and take readings from instruments

to teach how to measure the potential energy of a body raised above the ground and a deformed spring; compare two values of the potential energy of the system.

Developing:

development of students' thinking, the formation of their own acquisition and application of knowledge, observation and explanation of physical phenomena;

development of the ability to analyze and draw conclusions based on experimental data.

Educational:

encourage students to overcome difficulties in the process of mental activity, encourage tolerance and collectivism;

formation of cognitive interest in physics and technology.

Forms of organization of educational activities: frontal; individual; group.

Expected result of the lesson:

As a result of educational activities, in the planned lesson, students should:

To consolidate knowledge on the topic "The law of conservation of energy and its application."

Show skills of individual work, group work;

To improve previously acquired skills and abilities during the experiment through the use of physical instruments and measuring instruments for measuring physical quantities: friction force, body weight.

Develop the ability to analyze, draw up a report on the work done and draw a conclusion based on the result.

UMK: multimedia projector, tripod with clutch and foot; laboratory dynamometer; ruler; a load of mass m on a thread of length l, descriptions of laboratory work.

Lesson plan:

1. Organizational moment - 2 minutes(Title title, goals)

2. Update - 8 min

Checking d / s - frontal survey - 3 min.

What is potential energy? Her types?

What is kinetic energy?

What is total mechanical energy?

Name the law of conservation of mechanical energy.

Reception "Logbook" - filling in the column that I know! (Group discussion) - 5min

3. Performing laboratory work - 50 min.

Conducting safety briefings;

The study of l / r (to introduce students to the instruments, pay attention to the order of work).

registration of work by students in notebooks: topic, purpose, equipment, order of work.

performance of work by students, the teacher controls the work in groups.

Analysis and conclusion on work.

4. Fixing - 10 min.

Students answer questions individually.

5. Reflection. - 8 min.

Return to the purpose of the lesson: discussion, how does the force of friction depend on the weight of the body?

Filling in the logbook.

Questions for groups:

"Who thinks that he worked actively in the lesson? Raise your hands"

Do you think you have achieved the right result?

6. Homework: learn § - 2 minutes.

Lab #3 Attachment 1.

Topic: Study of the law of conservation of mechanical energy.

Objective: learn how to measure the potential energy of a body raised above the ground and a deformed spring; compare two values of the potential energy of the system..

Equipment: tripod with clutch and foot; laboratory dynamometer; ruler; weight load m on a thread of length l.

Theoretical part

The experiment is carried out with a weight attached to one end of a string of length l. The other end of the thread is tied to a dynamometer hook. If the load is lifted, then the dynamometer spring becomes undeformed and the dynamometer needle shows zero, while the potential energy of the load is due only to gravity. The weight is released and it falls down stretching the spring. If the zero point of the potential energy of the interaction of the body with the Earth is taken as the lower point that it reaches when it falls, then it is obvious that the potential energy of the body in the gravity field is converted into the potential energy of the deformation of the dynamometer spring:
mg (l+Δl) = kΔl 2 /2 , where Δl- maximum extension of the spring, k- its rigidity.

The difficulty of the experiment lies in the exact determination of the maximum deformation of the spring, since the body moves quickly.

Instructions for work

To perform the work, the installation shown in the figure is assembled. The dynamometer is fixed in the foot of the tripod.

1. Tie the weight to the thread, tie the other end of the thread to the dynamometer hook and measure the weight of the weight F t = mg(in this case, the weight of the load is equal to its gravity).

2.Measure the length l the thread on which the load is tied.

3. Raise the load to point 0 (marked on the dynamometer).

4. Release the load, measure the maximum elastic force with a dynamometer F ynp and ruler maximum spring extension Δl, counting it from the zero division of the dynamometer.

5. Calculate the height from which the load falls: h = l + ∆l(this is the height by which the center of gravity of the load is shifted).

6. Calculate the potential energy of the lifted load E" P = mg (l + ∆l).

7. Calculate the energy of the deformed spring E" P = kΔl 2 /2, where k = F ex /Δl

Substituting, the expression for k into the energy formula E" P we get E" P = ;F ex ∆l/2

8. Record the results of measurements and calculations in the table.

9. Compare energy values E" P and E" P. Think about why the values of these energies do not match exactly.

10. Make a conclusion about the work done.

Course of laboratory work 5. Studying the law of conservation of mechanical energy

1. Assemble the installation shown in the figure.

3. After lifting the weight so that the thread sags, install the clamp on the dynamometer rod near the limit bracket.

4. Raise the load almost to the dynamometer hook and measure the height of the load above the table (it is convenient to measure the height at which the lower edge of the load is located).

5. Release the load without pushing. Falling, the load will stretch the spring, and the latch will move up the rod. Then, stretching the spring by hand so that the latch is at the restrictive bracket, measure and

6. Calculate: a) the weight of the cargo; b) increase in the potential energy of the spring c) decrease in the potential energy of the load .

7. Record the results of measurements and calculations in a table placed in notebooks for laboratory work.

8. Find the value of the ratio .

9. Compare the resulting ratio with the unit and write down the conclusion in the notebook for laboratory work; indicate what transformations of energy occurred when the load moved down.

Laboratory works. 2014

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