University of San Carlos-Basic Education Department

Paref Springdale School Inc. THE LEADING SCHOOL OF CHARACTER EDUCATION IN THE SOUTHJ. Solon St., Lahug, Cebu City

PHYSICS

The Turning Point

Center of Gravity and Torque

Quarter:3rd QuarterNo. of Sessions :5 Sessions; November 26-29, 2012

CONTENT STANDARD: No rotation is produced when the torques balance each other.

PERFORMANCE STANDARD: Students will be able to determine whether a particular system is in rotational equilibrium or not.

TPO:Students will be able to apply the concept of equilibrium, center of mass and center of gravity and Torque to solve accordingly to balance opposing torque.

OVERVIEW:

The lesson will allow students to solve accordingly to balance opposing torque. Students will be worksheets of different cases, and so, theyre going to make each given system in rotational equilibrium. During a laboratory work to follow, varied masses will be balanced to a meter stick so students are free to manipulate the system until equilibrium is achieved. This plan covers the topics on center of mass, center of gravity, equilibrium, rotational equilibrium, and torque.

ObjectivesAssessment

Session 1

1. Analyze the real world interactions of balanced and unbalanced forces2. Demonstrate balance3. Locate the center of mass

4. 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.5. Describe some relevant daily life examples.6. Define and calculate moments using formula Torque= lever arm x force

7. Appreciate the concept of Torque in the real world scenario8. State and apply principle of moments for a body in equilibrium to solve problems.

8. Measure student learning development and progress

Quick feedback and questioning techniques are often done to facilitate discussion and teacher-student communication.Worksheets are given to check student understanding.Experimentation is done to assess their ability to apply their knowledge to a performance task and to be able to investigate the concept behind hands-on.

Summative test is to gauge student learning.

Lesson Proper

SESSION 1Center of Mass and Center of Gravity EXPLORE1. Introduce the concept of center of gravity using a regularly-shaped meter stick.

2. Expose students on locating center of gravity of donut and boomerang. Ask the students if its possible to have a center of mass outside the object. How?FIRM-UP

3. Introduce the idea of support and center of mass. 4. Ask the students to rise and stay beside the wall. Now, let them stick one foot at the base of the wall, then, let them balance themselves after they raise their other foot from the ground. Ask why they think they actually tip over. DEEPEN5. Using the applications like the Leaning Tower of Pisa and the balancing acts in acrobatics, allow students to point out where the center of mass is located. Include also the L-shaped object. Try to elicit varied reasoning and correct alternative conceptions that are drawn.6. Now, go back to the L-shaped object. Try to balance it upturned. Ask why did it not balance.

CLOSURE

8. When the words rotation, tilt, move clockwise or counter clockwise or spin are said, ask students to recall what is fulcrum (as discussed in their science and technology) and how it is shown in the example. Ask them to locate it (by finger pointing). Also, ask if a force is present. How are they related? 9. Introduce the idea of fulcrum, the twisting force, axis of rotation and that of the lever arm distance. TorqueEXPLORE

10. Define Torque.11. Distinguish force from torque using a demonstration. Ask for a student volunteer to hold the stick on its one end with the stick extended horizontally. The, put a weight to be suspended at its midpoint. Ask him/her: What did you feel? As a follow up question, ask: what are you doing to actually oppose that tendency? Move the suspended mass to the end and ask again what the students feel. When the observation that you did not change the weight or force involved comes out, allow students to differentiate it from torque.

FIRM-UP

8. Discuss how the change of lever arm distance actually changes the torque.

9. Discuss the torque behind a common wrench. Include in the discussion what happens when the lever arm is not directly at right angle with the line of action of the force. 10. Students use levers every day to help make their daily tasks easier. Begin the discussion of the importance of levers by doing one of the two following things (or your own):

11. - For rooms with regular hinge-open doors: Have one student use their pinkie to swing open the door positioned near the outside edge of the door. Have another student/same student attempt to open the door with their pinkie near the hinge of the door. Ask the students which seemed easier, and have them think about why that could be. 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. DEEPEN12. Use the concept of seesaw to identify the pivot, the force and the perpendicular distance. Try one simple calculation to get torque. 13. Discuss Balancing of Torque, still with the aid of the seesaw concepts.14. Show some problems related to Torque especially the problem on the Torques on a plank.TRANSFER/ CLOSURE

15. Show the video on the problem on torques on a plank.

16. Ask students to make a project about torque. The project is to capture or find an image wherein the idea of Torque is applied. An essay, explaining the Physics behind it--- torque---, should be attached. The project is due Thursday so that they have enough time to process their output.

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