Massachusetts Comprehensive Assessment System

2019, High School Intro Physics

Question 32: Open-Response

Reporting Category: Motion and Forces
Standard: 2.2 - Interpret and provide examples of how energy can be converted from gravitational potential energy to kinetic energy and vice versa.
Standard: Sci.HS.PHY.3.01 - Use algebraic expressions and the principle of energy conservation to calculate the change in energy of one component of a system when the change in energy of the other component(s) of the system, as well as the total energy of the system including any energy entering or leaving the system, is known. Identify any transformations from one form of energy to another, including thermal, kinetic, gravitational, magnetic, or electrical energy, in the system. Clarification Statement: Systems should be limited to two or three components and to thermal energy; kinetic energy; or the energies in gravitational, magnetic, or electric fields.

Inflatable launchers are large, air-filled bags that float on the surface of the water at lakes, water parks, and community pools. A launcher works by transferring energy from one person to another. A person sitting on a launcher is launched into the air when another person jumps onto the bag. The diagram shows a boy and a girl using an inflatable launcher at a lake.

The 75 kg girl is standing on a platform 15 m above the top of the launcher.

a. Calculate the gravitational potential energy of the girl relative to the top of the launcher. Show your calculations and include units in your answer.

The girl steps off the platform and lands on the launcher.

b. Describe how the girl’s kinetic energy and gravitational potential energy change during the time interval that begins when she steps off the platform and ends just before she lands on the launcher.

The boy is launched several meters into the air but wants to be launched higher.

c. Describe one change that could be made so that the boy would be launched higher. Explain your reasoning.

Scoring Guide for Idea Development

Select a score point in the table below to view the sample student response.

Score	Description
4	The response demonstrates a thorough understanding of how to interpret energy conversions between gravitational potential energy and kinetic energy. The response correctly calculates the potential energy of the girl and clearly describes how the girl's kinetic and potential energy change as she falls to the launcher. The response clearly describes and explains a change that would cause the boy to be launched higher.
4
3	The response demonstrates a general understanding of how to interpret energy conversions between gravitational potential energy and kinetic energy.
2	The response demonstrates a limited understanding of how to interpret energy conversions between gravitational potential energy and kinetic energy.
1	The response demonstrates a minimal understanding of how to interpret energy conversions between gravitational potential energy and kinetic energy.
0	The response is incorrect or contains some correct work that is irrelevant to the skill or concept being measured.

Note: There are 2 sample student responses for Score Point 4.

High School Intro Physics

Question 12: Waves and Radiation

Question 23: Motion and Forces

Question 32: Motion and Forces

Question 44: Heat and Heat Transfer

Question 45: Electromagnetism

Return to the MCAS 2019 Student Work Directory

Last Updated: May 5, 2020