Mechanics: Momentum and Collisions

Momentum and Collisions: Audio Guided Solution

Problem 20:

A Roller Derby exhibition recently came to town. They packed the gym for two consecutive weekend nights at South's field house. On Saturday evening, the 68-kg Anna Mosity was moving at 17 m/s when she collided with 76-kg Sandra Day O'Klobber who was moving forward at 12 m/s and directly in Anna's path. Anna jumped onto Sandra's back and the two continued moving together at the same speed. Determine their speed immediately after the collision.

Audio Guided Solution

Habits of an Effective Problem Solver

  • Read the problem carefully and develop a mental picture of the physical situation. If necessary, sketch a simple diagram of the physical situation to help you visualize it.
  • Identify the known and unknown quantities in an organized manner. Equate given values to the symbols used to represent the corresponding quantity - e.g., m = 1.50 kg, vi = 2.68 m/s,  F = 4.98 N, t = 0.133 s, vf = ???.
  • Use physics formulas and conceptual reasoning to plot a strategy for solving for the unknown quantity.
  • Identify the appropriate formula(s) to use.
  • Perform substitutions and algebraic manipulations in order to solve for the unknown quantity.

Read About It!

Get more information on the topic of Momentum and Collisions at The Physics Classroom Tutorial.

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