Lesson 11: Inertial and Non Inertial Frames of Reference
Overview:
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This lesson will help you in the real world if you ever wanted to buy a fish and save some money. If a person weights a fish of mass m on a spring scale attached to the ceiling of an elevator, the scale will read different for when the elevator accelerates either upward or downward, but yet remain the same if the elevator moves with constant velocity.
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Curriculum Expectations:
Specific Expectations:
B1.1 Analyse a technological device that applies the principles of linear or circular motion
(e.g., a slingshot, a rocket launcher, a race car, a trebuchet).
B2.1 Use appropriate terminology related to dynamics, including, but not limited to: inertial and non-inertial frames of reference, components, centripetal, period, frequency, static friction, and kinetic friction.
B2.5 Analyse, in qualitative and quantitative terms, the relationships between the motion of a system and the forces involved (e.g., a block and algebraic equations to solve related problems sliding on an inclined plane, acceleration of a pulley system), and use free-body diagrams and algebraic equations to solve related problems.
B3.1 Distinguish between reference systems (inertial and non-inertial) with respect to the real and apparent forces acting within such systems (e.g., apparent force in a rotating frame, apparent gravitational force in a vertically accelerating frame, real force pulling on the elastic of a ball-and-paddle toy).
B1.1 Analyse a technological device that applies the principles of linear or circular motion
(e.g., a slingshot, a rocket launcher, a race car, a trebuchet).
B2.1 Use appropriate terminology related to dynamics, including, but not limited to: inertial and non-inertial frames of reference, components, centripetal, period, frequency, static friction, and kinetic friction.
B2.5 Analyse, in qualitative and quantitative terms, the relationships between the motion of a system and the forces involved (e.g., a block and algebraic equations to solve related problems sliding on an inclined plane, acceleration of a pulley system), and use free-body diagrams and algebraic equations to solve related problems.
B3.1 Distinguish between reference systems (inertial and non-inertial) with respect to the real and apparent forces acting within such systems (e.g., apparent force in a rotating frame, apparent gravitational force in a vertically accelerating frame, real force pulling on the elastic of a ball-and-paddle toy).
Success Criteria:
- Compare and contrast inertial vs. non-inertial frames of reference.
- What are fictitious forces?
- Suppose you stand on a scale inside an elevator, what is the scale reading when the elevator (i) accelerates upwards (ii) accelerates downwards (iii) moves with uniform motion (iv) stays at rest?
- What does it mean to have an apparent weight?
Time Allocation: 1 hour
Learning Activities:
Read pages 108 - 112 from Nelson 3.1
In the playlist below, video:
- Will give a short lecture on six different scenarios of what a person's apparent weight will be on a scale in an elevator when the elevator is accelerating and decelerating.
- Will show your how to find the apparent mass of a man when the elevator is accelerating and decelerating.
- Will show you how to calculate the tension of a hanging 5kg object in an accelerating elevator.
Practice questions 1, 2, 3, and 4 on page 110.
Practice question 1 on page 112.
Practice question 1 on page 112.
Task:
Solve questions 1, 2, and 6 from Nelson 3.1 Review on page 113.
Optional Extension:
Optional Extension:
- Solve questions 7, and 8 on page 113.
- Practice questions 2, and 3 on page 112.
Reflect:
When a bus starts moving from rest, what force is acting on you when you begin to move in the opposite direction of acceleration?
