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A2L Item 142

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

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

Which stops in the shorter time?

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

Answer

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