A2L Item 142

• Description: Identify the block that stops in least time.
• Goal: Reasoning with forces and kinematics
• Source: UMPERG-ctqpe60 variant
• Keywords: Dynamics, Forces, Friction, Mechanics

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The question for students:

Two blocks, M₂ = M₁ but of different sizes, having the same speed, move from a frictionless surface onto a surface having friction coefficient μ_k.

Which stops in the shorter time?

1. M₁
2. M₂
3. Both stop in the same time
4. Cannot be determined

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Commentary for teachers:

Answer

(3) Both blocks will experience the same acceleration. If they have the same initial velocity, they will stop in the same time.

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