A2L Item 166

• Description: Identify the correct principle to solve the problem most efficiently.
• Goal: Problem solving and developing strategic knowledge
• Source: UMPERG-ctqpe104
• Keywords: Displacement, Forces, Mechanics, Problem Solving, Strategic Approach

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The question for students:

You are given this problem:

{: .image-right } A block sits on a frictionless incline. Given the mass of the block, the angle of incline, the distances d₁ and d₂, and that the block starts from rest, find the time to travel from d₁ to d₂.

What principle would you use to solve the problem MOST EFFICIENTLY?

1. Kinematics only
2. F = ma or Newton’s laws
3. Work-Energy theorem
4. Impulse-Momentum theorem
5. Angular Impulse-Angular Momentum
6. 1 & 2
7. 1 & 3
8. 2 & 3
9. None of the above
10. Not enough information given

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Commentary for teachers:

Answer

(6) Students responding #1 are relying on memory and would have difficulty if a force other than gravity was involved.

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