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					      Physics Lesson Plan

Topic: Introduction to Moment

    In partial fulfillment of the requirements for

          QCP 521 Teaching of Physics II

      Done by:     Cao Huijie (S7879403H)

      Lecturer:    A/P Yap Kueh Chin

    Supervisor:    A/P Chen Lai Keat

          Date:    April 7, 2011

Lesson Plan
Topic :               Turning Effect of Forces (Introduction to Moment)
Duration:             70 minutes (double period)
Target Class :        Secondary 3 Express.

Instructional Objectives:     At the end of lesson, students should be able to:

  1.   Describe the moment of a force in terms of its pivot, force applied and the perpendicular
       distance from the pivot to the line of action.
  2.   Describe some relevant daily life examples.
  3.   Define and calculate moments using formula M  F  D
  4.   State and apply principle of moments for a body in equilibrium to solve problems.

Prior Knowledge :     Before the lesson, students shall be able to:

  1.   State and apply Newton‟s law of motion.
  2.   Interpret and construct force diagram.
  3.   Construct perpendicular lines from a point to a line.

New Concepts/Terms:

                               Turning Effect of Forces

                                      is also known as

                                   Moment or Torque

                               can be
                                        calculated by

   Anti-clockwise                                               0.25 m
                                      M  F  D
                                      [SI units: Nm]

Learning Aids & Resources :

       Set Induction :          A half-metre rule

       IT :                     i)      PowerPoint slides and overhead projector
                                ii)     Video demonstration on seesaw candle

       Non-IT                   i)      Worksheets (Appendices A, B, C)
                                ii)     Whiteboard and markers
                                iii)    Wrenches

       Hands-on :               21 sets of the following apparatus:
                                a half-meter rule, a mass of 50g, a mass of 100g, string and

Set Induction :

           Ask students to observe and spot the difference in the way you drop the half-meter
            rule, as the following diagram depicts. One is to hold the meter rule at two ends and
            let go both ends simultaneously to allow free fall. The other is to hold the meter rule
            at two ends and release only one end, so the rule swings down towards the other end.

                               hand                                       hand


           Use this activity to introduce pivot and turning effect of forces (moment or torque)

           Get a student (probably a big guy) to open the classroom door as he usually does.
            Then ask him to open the door by only pushing near the hinge. He will realize it is
            extremely difficult to do so. If the class is not convinced, ask a few more students to

           Ask the class to identify the pivot in this case and note the turning effect of the push
            on the door. Get the class to see the difference is the distance from the pivot.

           Introduce the concept of moment or torque.

Lesson Development :

1) Everyday applications

The trigger activity uses the simple action of door opening to let students appreciate physics in
our life. And more daily examples (wrench, crane, can opening etc) are introduced later to bring
relevance of moment to the classroom.

2) Student participation

This will be a student-centred lesson whereby the class works in pairs to investigate the principle
of moment. They will be given the necessary apparatus and worksheet (Appendix B) to deduce
the relationship between clockwise moment and anti clockwise moment. Some students will
also present their solutions to some problems on the board. This helps to keep the students on
task and build up their confidence.

3) Experimental activities

The exploration activity on principle of moment provides hands-on experience and promotes
inquiry thinking to enhance students‟ learning.

4) Collaborative learning

After each pair has done the investigative activity, they will share their findings with the class
and answer any questions pertaining to their findings.

5) IT – Interactive multimedia

The lesson will use PowerPoint slides as visual aides and show a video demonstration of seesaw
candle to illustrate the principle of moment.

Lesson Closure:

Get the class to reflect on their learning and share with the class.        Summarize the main
objectives of the lesson.


   GCE „O‟ Levels Physics Syllabus (5052)
   Video demonstration of seesaw candle

Lesson Plan Proper
Microteaching session is highlighted in italics.

   Frame                    Teaching/Learning Activities                       Materials                  Rationale                     Key questions

            Induction Activity:
            Ask students to observe and spot the difference in the way
     5      you drop the half-meter rule. One is to hold the meter rule                                                              What‟s the main
            at two ends and let go both simultaneously to allow free fall.    Half -Meter        By comparing two different           difference in the way I
            The other is to hold the meter rule at two ends and release          Rule           types of falling, it introduces       drop the rule?
            only one end, so the rule swings down towards the other end.                         pivot and turning effects of        How would you
                                                                                                    forces to the students.           describe the motion of
                                                                                                                                      the rule?
            Get a student (probably a big guy) to open the classroom
            door as he usually does. Then ask him to open the door by
            only pushing near the hinge. He will realize it is extremely
            difficult to do so. Ask class to think of some daily life        Blackboard and    This simple everyday example          What has changed in
            examples of moments.                                                 marker        brings relevance of moments to         these two different
                                                                                              our life and get students examine       ways of opening the
            Show two wrenches, one with long arm, the other with short                               the rationale behind.            door?
            arm. Ask students which wrench would they choose to                                                                      Could you identify the
            unscrew a bolt.                                                    Wrenches                                               pivot in this case?

            Development of Concepts:

            Definition and Calculation of Moments

     5        1. Introduce the definition of moments (formula and                              Through comparing to formula          Have you seen the
                 units), stressing on the meaning of “perpendicular                           of work done, it promotes lateral       formula somewhere
                 distance”, and comparing with the definition of work                           thinking and linkage to prior         else? Also involves
                 done. Go back to the examples of two wrenches with
Frame                  Teaching/Learning Activities                      Materials                  Rationale                      Key questions
             different length and door-opening activity, ask           Whiteboard and             knowledge.                     force and distance?
             students to apply the formula to explain that the            markers                                               Why do you feel it‟s
             moment required to turn an object is fixed, while                                                                   harder to open the
             distance is longer, force required will be less.                                                                    door if you push near
                                                                                                                                 the hinge?

          2. Show some daily life examples of moments, get              Worksheet        Make sure students understand          Is this the correct way
             students to identify the pivot, the force and construct    appendix A        the perpendicular distance is          of drawing
             the perpendicular distance. During the construction,         (OHT)         from pivot to the line of force by       perpendicular
             the line of force can be extended if necessary. Can ask                         showing the examples.               distance? (non-
             students to present their answer on the transparency.                                                               example)

 5        3. Using wrench example, ask students to choose the                            Let students realize that force        Which direction shall
             direction to apply force on the wrench. At the same       Wrench, Clock     and distance will influence the         I apply the force? F1,
             time introduce clockwise and anticlockwise moments        (in classroom)      outcome of turning effects.           F2 or F3?
             using the wrench example.                                                      Use clock to illustrate the
                                                                                             direction of moments.

 10       4. Let students try some simple questions on calculation                                                              What happened if I
                                                                       Whiteboard and
             of moments. Ask a few students to present their              markers           It‟s easier for students to          change the question to
             answers on the board if time allows. And use the                            visualize and understand using          “find the moment
             working examples to investigate moment about                                      numerical examples.               about point B
                                                                        appendix C
             different points, students will realize the importance                                                              instead”?
             of identifying the pivot.

        Principle of Moments
                                                                                                                                Have you ever noticed
 5        1. Recall the concept of clockwise and anticlockwise                           Visual aides to show real life          how a crane keeps its
             moments, show pictures of cranes to let students           PowerPoint         application of moments.               balance?
             ponder how to balance the moments.                           slides

Frame                  Teaching/Learning Activities                         Materials                   Rationale                      Key questions
  15      2. Inquiry Activity (Pairwork)                                                                                            Is there any pattern
             Give clear instructions and expectations before               PowerPoint            The inquiry and induction           you have recognized?
             grouping the students. Ask one student to tie the                Slides           approach is taken here to let
             string at 25 cm mark to keep the rule balanced. Then        Half-meter rule,   students investigate the principle
             put the 100g at one side of the string and the 50 g on      string, 50g and     of moments themselves. This is
             the other side to keep the rule balanced. The other          100g masses.      to promote a sense of ownership
             student fills the data table in the worksheet to record                            towards students‟ learning.
             down the mass and the corresponding distance. Let             Worksheet
             the students share their findings and induce the              appendix B
             principle of moments.

 10       3. Ask the students to draw the force diagram of their           Worksheet        Pointing out students‟ common           Are these all the
             experiment. Highlight the presence of gravitational           appendix B        mistakes helps them to avoid            forces present on the
             force on all objects on earth. If the gravitational force                        making the same mistakes.              rule?
             is passing through the pivot, no moment is resulted           Video clip                                               Why is the candle
             due to zero distance. Relate the previous crane                (Seesaw                                                  seesawing?
             example and ask students to apply the principle to             Candle)
             explain how the crane keeps its balance. Show the
             video of seesaw candle to get students explain the
                                                                           Worksheet        Practice to reinforce the concept.
          4. Show one working example using principle of                   appendix C
             moments. Ask students do a few more questions, in
             increasing difficulty.

 5      Closure:

          1. Let students write down their reflection of the lesson.                         Encourages reflective learning         What are the most
             Then ask a few students to share what they have learnt                            and makes learning more               important things you
             from this lesson.                                                                conscious and visible to the           have learnt in this
                                                                                                       students.                     lesson?

  Frame                     Teaching/Learning Activities                        Materials                   Rationale                      Key questions
              2. Summarize the concepts taught in this lesson: the
                 definition of moments, its application in our daily life,
                 the principle of moments.
              3. Ask students to finish the questions in the worksheet
                 as homework. Tell them that you will check their
                 work in the next lesson.

Microteaching Reflection

       Through the process of micoteaching, I have learnt the following points:

      Be very thorough and confident about the content I am teaching. I realized that students could ask any questions related or non-related to the topic
       you are teaching, thus it‟s essential to be very familiar with the content and prepare beyond the requirement of the syllabus. For example, only by
       observing my colleague‟s microteaching, I realize some of my misconceptions, like speed of wave is only affected by the medium it is traveling, not
       by the wave‟s frequency or wavelength as the equation may have suggested v  f .
      Listening to my colleague‟s microteaching, I realize the importance of student-centred teaching. There are various ways to engage the students, like
       doing investigative activities, getting feedback from the students, showing video clips or simulations. In comparison, real life demonstration is more
       effective to bring the message across than a demonstration video clip.
      Lesson plan helps greatly in structuring the lesson and smooth transition of the contents. It makes me conscious to decide the flow of the ideas so
       that students can follow the concepts and don‟t get lost in the lesson. The lesson plan also helps me to identify the rationales behind each teaching
       activities, so that it‟s clear to me which skills are not developed in the lesson and helps me to improve my teaching approaches.
      In demonstration or illustration of concepts, it‟s important to convince the students what you are saying is true, like if you have two magnets, you tell
       students one magnet is stronger than the other, to verify this, you show that the stronger magnet can attract a lot more paper clips than the weaker
       magnet. This helps students to clear their doubts and believe in what they are seeing.
      I also note that if the demonstration produces quite a few results or you have quite a few questions related to the demonstration, it‟s beneficial to
       record the observations or students‟ answers on the whiteboard. This helps students to stay focused and also makes it much easier for you to refer to
       while illustrating the concepts.

       I find the microteaching very helpful and beneficial, it opens my mind to various ideas of teaching physics topics and brings my attention to some
       common pitfalls. Through sharing and observation, we learnt each other‟s strength and weakness.

Appendix A                           Daily Application of Moments

Draw on the following diagram the pivot, the force and the perpendicular distance.
Indicate whether the direction of the moment too, clockwise or anticlockwise.




                                                            Tin can

                                                                   effort P

Appendix B                      Investigation on Principle of Moments
          To analyze the effects of clockwise and anti clockwise moment
          To investigate the conditions to keep an object at equilibrium
          To induce the principle of moments

       A half-metre rule
       A mass of 50g and a mass of 100g
       Some strings

1.   Use the string to suspend the rule, make sure the rule is balanced. At which marking shall you tie the

2.   Place the 50g mass anywhere on one side of the rule, what effect does it have on the rule? What‟s the
     moment and the direction of the moment? Show your working clearly.

3.   Place the 100g mass on the other side of rule to keep the rule balanced. At which marking shall you
     put the 100g for this to work? What‟s the moment produced by this 100g mass and the direction of
     the moment? Show your working clearly.

4.   Repeat step 2-3 five times and record the data in the following table. g = 10m/s2

     Weight of 100g mass __________________ Weight of 50g mass____________________

                       1              2              3              4               5              6
                                  Direction                                    Direction of
                                                 Moment                                         Moment
                  Distance of    of moment                                       moment
                                               produced by     Distance of                    produced by
                  100g mass       produced                                     produced by
      Data set                                  100g mass       50g mass                       50g mass
                  from pivot       by 100g                                      50g mass
                                                 about the     from pivot                      about the
                     (cm)        mass about                                     about the
                                               pivot (Nm)                                     pivot (Nm)
                                  the pivot                                       pivot





5.   Did you observe any pattern in the values you obtained from column 3 and 6? How about column 2
     and 5?

6.   Based on your investigation, what do you think are the necessary conditions for an object to be
     balanced (in equilibrium)?

7.   Draw a force diagram of the experiment while the rule is balanced with 100g and 50g masses on it.
     Indicate ALL forces acting on the rule.

Appendix C                         Exercises on Turning Effect of Force

  1. Find the moment of the exerted force about the pivot O for the following situations, show your
     working clearly.

                         5N                        5N
                                          0.75 m
   O                                  O                                  O
           1.5 m                               1.5 m                            1.5 m       5N

  2. Find the moment of the exerted force about the pivot O for the following situations:

       1.3 m


               1.5 m          5N

                          10 N

               1.5 m

       Hint: use trigonometry

3. A metre rule with uniform weight is balanced at its centre by two weights, X and Y as shown in
   the figure below. If the weight of X is 40 N and the weight of Y is 60 N, find the distance of
   weight Y from the support.
                         0.3 m                        d

         40N                                                   60N

4. A metre rule with uniform weight is balanced by a weight, Z as shown in the figure below. If the
   weight of Z is 40 N and the weight of the ruler

               0.1 m

        40N                               W

5. A man of mass 72 kg stands on one end of a see-saw. Two children sit on the opposite end as
   shown in Figure 6. If the pivot is assumed to be smooth, which of the following gives the correct
   combination of the masses of the children that are able to balance the man?

                                                           0.50 m

                Man                           1.00 m
                            1.50 m                         A

              Child A                 Child B

     A        40 kg                   50 kg
     B        45 kg                   42 kg
     C        50 kg                   40 kg
     D        54 kg                   54 kg

6. A painter of weight 1000N stands 1.0m from the left-hand end of a uniform plank which is 5.0m
   long and weighs 800N. The plank is supported by two trestles each 0.5m from the opposite ends.
   The diagram below shows the two upward forces P and Q acting on the plank due to the trestles.

                 0.5m                                          0.5m
                        P                                    Q

     (a) Complete the diagram above to show any other forces which are acting on the
         plank. Name each of these forces.
     (b) What is the magnitude of the total downward force exerted on the trestles?
     (c) What is the magnitude of the total upward force exerted by the trestles on the
     (d) By taking moments about the left trestle, calculate the upward force exerted on
         the plank by the other trestle.


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