AP Physics 1 2017 Exam - Free Response Question Review

Presenter: Alan, Bothell Stem Coach

Overview of the Problem

• Physics class demonstrates using a low-friction slide to launch a block horizontally from a lab table.
• Two teams: identical blocks, starting at the same height D above the tabletop.
• Team 2's table is lower; uses a ramp to ensure the block leaves the slide at the same height H above the floor.
• Both blocks are released and land the same distance from the tables.

Key Concepts

• Conservation of Energy: No frictional energy losses assumed.
• Potential Energy Conversion: Height is converted to kinetic energy as the block moves down the slide.
• Horizontal Launches: Both blocks leave the slides horizontally.
• Initial Setup: Block on higher table has more potential energy as D > D - H.

Analysis and Reasoning

First Experiment Results

• Block Speed & Distance:
  • Block 1 (higher table) has more potential energy, thus a higher final speed.
  • Block 1 lands further because it starts with more potential energy.

Second Experiment Results

• New Setup: Same table height, different slide shapes.
• Landing Distance:
  • Both blocks land the same distance as the potential energy conversion (to kinetic energy) is identical.
• Time of Flight:
  • Both blocks have no vertical initial velocity when launched and the same height for the fall.
  • Thus, both blocks will hit the floor at the same time due to the influence of gravity.

Additional Considerations

• Clarification from Scoring Guidelines:
  • Initial misunderstanding: Slide speed difference was overlooked.
  • Block 1 accelerates faster on its steeper slide portion, even though flight time remains unaffected.

Lessons Learned

• Important Concept: Conservation of potential and kinetic energy, relevance in height changes, and uniform gravity effects.
• Critical Insight: Realizing slide shape impacts time taken to reach launch height but not flight time.

Conclusion

• Importance of careful interpretation of problem details and scoring guidelines.
• Encouragement to viewers: Problem-solving without previewing solutions can lead to valuable learning experiences.