SHS2 Physics · Semester 1 Week 11: Kinematics

Lesson notes

Learning Objectives

Indicator: 2.1.3.LI.4 - Calculate maximum and minimum tension in a string.

By the end of the lesson, learners can:

Describe the forces acting on a body whirled in a vertical circle at the top and bottom of the circle.
Derive the expressions for maximum tension (at the bottom) and minimum tension (at the top) in the string.
Calculate the maximum and minimum tension in a string for given values of mass, speed and radius.
Explain how the tension in the string changes continuously as the body moves around the vertical circle.
Relate the tension at the top of the circle to the minimum speed required to keep the string taut.

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Curriculum details

Strand: Mechanics and Matter (Strand 1)
Sub-strand: Kinematics (1.3)
Content standard: 2.1.3.CS.2 - Demonstrate knowledge and understanding of circular motion. 2.1.3.LO.2 Use the concept of circular motion to explain how the earth is kept in its path.
Indicator: 2.1.3.LI.4 - Calculate maximum and minimum tension in a string.
Suggested placement: Semester 1, Week 11 (Week 11 of the year)
Our suggestion, laid out in curriculum order across three terms of twelve weeks. NaCCA does not fix the week, so follow your school's scheme of learning.
Curriculum reference: NaCCA curriculum document, p. 102

Exemplars (from the NaCCA curriculum)

Talk for Learning: Discuss the relationship between the weight of a body tied to a string and whirled round in a vertical circle, the tension in the string and the centripetal force on the body
Foster an inclusive and supportive learning environment.
Assessment (2.1.3.AS.4). The document marks these depth-of-knowledge levels for this indicator: Level 3 Strategic reasoning.
Teaching and Learning Resources:
- Audio-visuals
- Internet
- Projectors
- YouTube
- Interactive virtual laboratory