2 | FRQ (Question 4/5: Short Answer) | Practice Sessions | AP Physics 1

Kristin Gonzalez-Vega introduces the video series focused on AP Physics 1 free response questions (FRQs). She explains the structure of the upcoming videos, which will cover strategies for answering different types of FRQs, including the shorter 7-point questions and longer 12-point questions. The session specifically focuses on question 5 from the 2020 AP exam, which involves a spring with an unknown constant, a mass, and a motion detector. The goal is to calculate the spring constant using the period equation and to understand the different approaches to solving such problems. The importance of showing all work and using the correct formulas is emphasized, as well as the need to download the questions as PDF and prepare paper, a formula chart, and a calculator for active participation.

The video segment delves into the process of calculating the spring constant (k) from the given data and graph. Two methods are discussed: using the period equation (2π√(m/k)) and Hooke's law (mg = kx). The first method involves using the period of oscillation from the graph and the known mass to solve for k. The second method uses the change in equilibrium position due to the mass hung on the spring. The importance of showing all steps and maintaining units is highlighted. The video also explains how to earn points on the AP exam by demonstrating a clear understanding of the concepts and correctly applying them to the problem.

This part of the script focuses on analyzing the provided graph to understand the conservation of energy in the object-spring-Earth system at two different times. The key is to recognize that the total mechanical energy remains constant when no external forces are acting on the system. The explanation involves comparing the kinetic energy at the two times, which is determined by the slope of the graph (indicating speed). The potential energy is then discussed, emphasizing that since the total energy is conserved and the kinetic energy is the same at both times, the potential energy must also be the same. The video encourages the use of the graph to support the explanation and to understand the significance of the system's boundaries and the conservation laws in physics.

The script outlines the steps to predict the new equilibrium position when a spring with a spring constant of 4k is used, and the object is the same 0.5 kg mass. The focus is on applying Hooke's law and understanding the relationship between the spring constant and the stretch of the spring. The new equilibrium position is calculated to be 0.9 meters above the motion detector. The video then discusses the process of drawing the motion curve for the object on a graph, including determining the period, amplitude, and starting position. The importance of labeling the vertical axis with the correct numerical scale and ensuring the graph is consistent with the given information is emphasized.

In the concluding segment, Kristin Gonzalez-Vega summarizes the key points covered in the video and encourages students to continue practicing free response questions. She highlights the importance of understanding the concepts and applying them correctly, even if a mistake is made in one part of the problem. The video emphasizes the AP exam's approach to grading, which rewards good physics understanding and consistency, even in the face of errors. Students are encouraged to persist and continue practicing, ensuring they understand the material and can apply it effectively.