PHY 101L - Physics I Laboratory
Module Four Lab Report: Gravity | Questions & Answers
Free Fall, Kinematics, Data Analysis, Error Calculation | Title 62 | 2026 Update
Assessment Module Four Lab Report - Questions & Answers (Title 62)
Questions 25 Multiple Choice (A-D) with Complete Solutions
Date July 8, 2026
Academic Year 2026-2027
Cognitive Level 30% Recall | 50% Application | 20% Analysis
Standards PHY 101L Experimental Physics Competencies, 2026 Lab Standards
, PHY 101L | Module Four Lab Report | Gravity | Title 62 | 2026
Section 1: Principles of Free Fall & Experimental Setup (Q1–Q7)
Q1. In a vacuum, a feather and a bowling ball are dropped simultaneously from the same height. Which statement best
explains why both objects strike the ground at the same time?
A. Air resistance acts equally on all objects regardless of shape or mass
B. The gravitational force is identical on both objects because their weights are equal
C. The acceleration due to gravity is inversely proportional to mass, so lighter objects accelerate faster to
compensate
D. In the absence of air resistance, all objects experience the same gravitational acceleration (g ≈ 9.80 m/s²)
regardless of mass, so both accelerate identically from rest [CORRECT]
Correct Answer: D
Rationale: Newton’s second law (F=mg) and gravitational law (F=GMm/r²) show that mass cancels, yielding a = GM/r² =
g for all objects. A is wrong because a vacuum has no air. B is wrong because the gravitational force (weight) depends on
mass. C incorrectly states g is inversely proportional to mass.
Q2. The accepted value of the acceleration due to gravity at sea level is g = 9.80 m/s². A student asks whether this value
changes with altitude. Which statement is most accurate?
A. g increases with altitude because the student is closer to the center of Earth’s mass distribution
B. g decreases with altitude because the gravitational force weakens with increasing distance from Earth’s center,
following an inverse-square relationship [CORRECT]
C. g remains constant at all altitudes because it is a universal constant
D. g increases with altitude because atmospheric pressure decreases, reducing buoyant forces
Correct Answer: B
Rationale: g = GM/r², so increasing r (altitude) decreases g. At the top of Mount Everest (~8,849 m), g ≈ 9.78 m/s². A
reverses the direction. C incorrectly treats g as universal. D confuses g with buoyancy.
Q3. In a free-fall experiment, why is it critical that the object is released from rest (initial velocity v■ = 0)?
A. Starting from rest ensures the kinematic equation simplifies to y = ½gt², allowing direct calculation of g from
measured y and t values without needing to account for initial velocity [CORRECT]
B. An initial velocity would violate Newton’s first law and prevent the object from falling
C. The object cannot be in free fall unless it begins with zero velocity at the exact release point
D. Starting from rest eliminates the effect of air resistance on the measurement
Correct Answer: A
Rationale: With v■=0, the equation y = y■ + v■t + ½gt² simplifies to y = ½gt² (with y■=0, taking downward as positive
y), making g = 2y/t² directly calculable. B misstates Newton’s first law. C is incorrect – any object under only gravity is in
free fall. D confuses initial velocity with air resistance.
Q4. A PHY 101L student sets up a free-fall apparatus by attaching an electromagnet to hold a steel ball at a known
height and a timing gate at the floor. What is the primary purpose of using an electromagnet release mechanism instead
of manually dropping the ball?
A. The electromagnet eliminates gravitational acceleration so only air resistance affects the fall
B. The electromagnet reduces the mass of the ball, making air resistance negligible
C. The electromagnet provides a consistent and reproducible release with minimal initial velocity and reduces
human reaction time error compared to a manual release [CORRECT]
D. The electromagnet ionizes the air around the ball, eliminating air drag during the fall
Correct Answer: C
Rationale: An electromagnet ensures the ball is released cleanly at t=0 without being pushed or held, reducing the
systematic error from inconsistent initial velocity. A, B, and D describe physically impossible effects.
Q5. A student is asked to identify which of the following is NOT a valid assumption in the ideal free-fall model used in
this lab:
A. The object falls in a vacuum (no air resistance)
B. The acceleration due to gravity is constant throughout the fall
C. The only force acting on the object is gravity
D. Air resistance increases proportionally with velocity and must be included in the calculation of g [CORRECT]
Page 2
Module Four Lab Report: Gravity | Questions & Answers
Free Fall, Kinematics, Data Analysis, Error Calculation | Title 62 | 2026 Update
Assessment Module Four Lab Report - Questions & Answers (Title 62)
Questions 25 Multiple Choice (A-D) with Complete Solutions
Date July 8, 2026
Academic Year 2026-2027
Cognitive Level 30% Recall | 50% Application | 20% Analysis
Standards PHY 101L Experimental Physics Competencies, 2026 Lab Standards
, PHY 101L | Module Four Lab Report | Gravity | Title 62 | 2026
Section 1: Principles of Free Fall & Experimental Setup (Q1–Q7)
Q1. In a vacuum, a feather and a bowling ball are dropped simultaneously from the same height. Which statement best
explains why both objects strike the ground at the same time?
A. Air resistance acts equally on all objects regardless of shape or mass
B. The gravitational force is identical on both objects because their weights are equal
C. The acceleration due to gravity is inversely proportional to mass, so lighter objects accelerate faster to
compensate
D. In the absence of air resistance, all objects experience the same gravitational acceleration (g ≈ 9.80 m/s²)
regardless of mass, so both accelerate identically from rest [CORRECT]
Correct Answer: D
Rationale: Newton’s second law (F=mg) and gravitational law (F=GMm/r²) show that mass cancels, yielding a = GM/r² =
g for all objects. A is wrong because a vacuum has no air. B is wrong because the gravitational force (weight) depends on
mass. C incorrectly states g is inversely proportional to mass.
Q2. The accepted value of the acceleration due to gravity at sea level is g = 9.80 m/s². A student asks whether this value
changes with altitude. Which statement is most accurate?
A. g increases with altitude because the student is closer to the center of Earth’s mass distribution
B. g decreases with altitude because the gravitational force weakens with increasing distance from Earth’s center,
following an inverse-square relationship [CORRECT]
C. g remains constant at all altitudes because it is a universal constant
D. g increases with altitude because atmospheric pressure decreases, reducing buoyant forces
Correct Answer: B
Rationale: g = GM/r², so increasing r (altitude) decreases g. At the top of Mount Everest (~8,849 m), g ≈ 9.78 m/s². A
reverses the direction. C incorrectly treats g as universal. D confuses g with buoyancy.
Q3. In a free-fall experiment, why is it critical that the object is released from rest (initial velocity v■ = 0)?
A. Starting from rest ensures the kinematic equation simplifies to y = ½gt², allowing direct calculation of g from
measured y and t values without needing to account for initial velocity [CORRECT]
B. An initial velocity would violate Newton’s first law and prevent the object from falling
C. The object cannot be in free fall unless it begins with zero velocity at the exact release point
D. Starting from rest eliminates the effect of air resistance on the measurement
Correct Answer: A
Rationale: With v■=0, the equation y = y■ + v■t + ½gt² simplifies to y = ½gt² (with y■=0, taking downward as positive
y), making g = 2y/t² directly calculable. B misstates Newton’s first law. C is incorrect – any object under only gravity is in
free fall. D confuses initial velocity with air resistance.
Q4. A PHY 101L student sets up a free-fall apparatus by attaching an electromagnet to hold a steel ball at a known
height and a timing gate at the floor. What is the primary purpose of using an electromagnet release mechanism instead
of manually dropping the ball?
A. The electromagnet eliminates gravitational acceleration so only air resistance affects the fall
B. The electromagnet reduces the mass of the ball, making air resistance negligible
C. The electromagnet provides a consistent and reproducible release with minimal initial velocity and reduces
human reaction time error compared to a manual release [CORRECT]
D. The electromagnet ionizes the air around the ball, eliminating air drag during the fall
Correct Answer: C
Rationale: An electromagnet ensures the ball is released cleanly at t=0 without being pushed or held, reducing the
systematic error from inconsistent initial velocity. A, B, and D describe physically impossible effects.
Q5. A student is asked to identify which of the following is NOT a valid assumption in the ideal free-fall model used in
this lab:
A. The object falls in a vacuum (no air resistance)
B. The acceleration due to gravity is constant throughout the fall
C. The only force acting on the object is gravity
D. Air resistance increases proportionally with velocity and must be included in the calculation of g [CORRECT]
Page 2
