Lesson 2: Equations of Motion
Overview:
In the last lesson we looked at how to solve motion problems by graphical analysis, in this lesson we will derive the equations of motion and apply them to solve problems related to motion. We will restrict to problems in one dimension. Then we will see how to modify the equations of motion for freely falling objects and solve related problems.
Curriculum Expectations:
Specific Expectations:
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.
B2.2 Solve problems related to motion, including projectile and relative motion, by adding and subtracting two-dimensional vector quantities, using vector diagrams, vector components, and algebraic methods.
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.
B2.2 Solve problems related to motion, including projectile and relative motion, by adding and subtracting two-dimensional vector quantities, using vector diagrams, vector components, and algebraic methods.
Success Criteria:
- Do the equations of motion apply if acceleration is not constant?
- Make a table of the 5 equations of motions, with their corresponding known and unknowns.
- Describe free fall.
- What is the approximation for the acceleration due to gravity on Earth?
Time Allocation: 2 hours
Learning Activities:
Read pages 17 - 20 from Nelson 1.2
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A green ball is thrown upward. We show its position vector, position vs time graph, velocity vector, velocity vs time graph, acceleration vector, acceleration vs time graph and energies (total mechanical, potential and kinetic) vs time graph.
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In the playlist below, video:
- Will show you how to calculate the final distances of a car traveling at various accelerations.
- Will explain the conceptual approach of an object in free-fall.
- Will show you how to calculate the final velocity of an object in free-fall.
- Will show you how to calculate the maximum height of an object thrown upward.
Practice questions 1 and 4 on page 19.
Practice questions 1 and 3 on page 20.
Practice questions 1 and 3 on page 20.
Task:
Solve questions 1, 2, 5, 6, and 7 from Nelson 1.2 Review on page 21.
Optional Extension:
Optional Extension:
- Practice questions 5 and 6 on page 19.
- Solve question 3 on page 21.
Reflect:
When a driver is forced to make a panic stop by pressing down on the brake as hard as possible, the car will undergo a large acceleration to stop. Think of different reaction times, and the implications, to the driver using cellphones while driving to come to a complete stop.
