RIO SALADO COLLEGE
PHY 111 — Introductory Physics
MIDTERM 1
Questions with Complete Solutions
Edition
Total Questions 100
Sections 7
Format Multiple Choice (A-D)
Cognitive Distribution 25% Recall | 50% Application | 25% Analysis
Style 70% Scenario-Based | 30% Direct Knowledge
Aligned With Rio Salado PHY 111 Syllabus; AAAS Vision & Change;
Introductory Physics Curriculum Standards (2026/2027)
Special Inclusions 25 Calculation | 15 Vector Resolution | 10 Graph Reasoning
Each question includes the correct answer and a 2-4 sentence rationale grounded in the Rio Salado
PHY 111 curriculum and standard physics problem-solving methodology.
, Section 1: Measurement, Units, & Scientific Notation
12 Questions | Cognitive levels: Recall, Application, Analysis
Q1: A student is calibrating a laboratory balance for a Rio Salado PHY 111 density lab. Which of the
following lists ONLY SI base units (fundamental quantities), as defined by the International System of
Units?
A. meter, kilogram, second, liter
B. meter, kilogram, second, newton
C. meter, kilogram, second, ampere, kelvin, mole, candela *[CORRECT]*
D. kilogram, second, kelvin, watt
Correct Answer: C
Rationale: The seven SI base units are meter (length), kilogram (mass), second (time), ampere (electric current),
kelvin (temperature), mole (amount of substance), and candela (luminous intensity). Liter (A) is a non-SI unit of
volume, newton (B) is a derived unit of force (kg·m/s²), and watt (D) is a derived unit of power. The Rio Salado PHY
111 curriculum emphasizes distinguishing base quantities from derived quantities as the foundation of dimensional
analysis.
Q2: In a workplace scenario, an engineer must convert a pressure reading. Which of the following is a
DERIVED unit (constructed from base units) rather than a base unit?
A. kilogram
B. newton *[CORRECT]*
C. second
D. kelvin
Correct Answer: B
Rationale: The newton is a derived unit defined as kg·m/s² (from F = ma). Kilogram (mass), second (time), and
kelvin (temperature) are all SI base units. The PHY 111 methodology requires students to express derived units in
terms of base units to verify dimensional consistency in formulas such as P = F/A.
Q3: A biologist measures a cell diameter of 25 μm (micrometers). To enter this value into a statistics
spreadsheet using millimeters, the correct conversion is:
A. 0.025 mm *[CORRECT]*
B. 0.25 mm
C. 2.5 mm
D. 0.0025 mm
Correct Answer: A
Rationale: The prefix micro (μ) equals 10 ⁶ and milli equals 10 ³. Therefore 25 μm = 25 × 10 ⁶ m = 0.025 ×
10 ³ m = 0.025 mm. Option B errors by a factor of 10, C by a factor of 100, and D by a factor of 10 in the opposite
direction. Mastering metric prefix conversion is essential for accurate scientific communication in PHY 111
laboratory work.
RIO SALADO PHY 111 - Midterm 1 (2026/2027) | Page 2
,Q4: A computer chip feature is advertised as 14 nm (nanometers). Expressed in meters using scientific
notation, this dimension equals:
A. 1.4 × 10 ⁹m
B. 1.4 × 10 ⁸ m *[CORRECT]*
C. 1.4 × 10 ⁷m
D. 1.4 × 10 ⁶m
Correct Answer: B
Rationale: The prefix nano (n) equals 10 ⁹, so 14 nm = 14 × 10 ⁹ m = 1.4 × 10 ⁸ m (the decimal is shifted one
place left, increasing the exponent by 1). Option A keeps the original coefficient, while C and D shift the decimal in
the wrong direction. PHY 111 students must be fluent in converting between metric prefixes and scientific notation.
Q5: A student derives a formula for speed v in terms of distance d and time t. Which equation is
dimensionally consistent?
A. v = d × t
B. v = d / t²
C. v = d / t *[CORRECT]*
D. v = t / d
Correct Answer: C
Rationale: Speed has units of [length]/[time]. In option C, d/t gives (m)/(s) = m/s, which matches. Option A gives
m·s (wrong), B gives m/s² (acceleration units), and D gives s/m (inverse speed). Dimensional analysis is a critical
PHY 111 problem-solving tool for catching algebraic errors before numerical substitution.
Q6: A field researcher records three measurements of a sample length: 12.4 cm, 12.37 cm, and 12.41 cm.
Reported with the correct number of significant figures, the sum equals:
A. 37.18 cm
B. 37.2 cm *[CORRECT]*
C. 37 cm
D. 37.180 cm
Correct Answer: B
Rationale: For addition/subtraction, the result is rounded to the same number of DECIMAL PLACES as the
measurement with the fewest decimal places. Here 12.4 cm has one decimal place, so the sum 37.18 cm rounds to
37.2 cm. Option A keeps extra digits, C rounds too aggressively, and D adds false precision. PHY 111 sig-fig rules
prevent over-reporting precision that the instruments cannot support.
RIO SALADO PHY 111 - Midterm 1 (2026/2027) | Page 3
, Q7: In a projectile calculation, a student multiplies 3.50 m by 2.1 s. The product, reported with the
correct number of significant figures, is:
A. 7.350 m·s
B. 7.35 m·s
C. 7.4 m·s *[CORRECT]*
D. 7 m·s
Correct Answer: C
Rationale: For multiplication/division, the result has the same number of significant figures as the factor with the
fewest sig figs. 3.50 has 3 sig figs; 2.1 has 2 sig figs. Therefore the product 7.35 must round to 2 sig figs: 7.4 m·s.
Option B incorrectly preserves 3 sig figs, A preserves 4, and D rounds to 1. PHY 111 stresses that sig figs
communicate measurement precision, not arbitrary decimal places.
Q8: The mass of a dust particle is measured as 0.0000048 kg. In correct scientific notation, this value is
written as:
A. 4.8 × 10ⁿ kg
B. 4.8 × 10 ⁶ kg *[CORRECT]*
C. 4.8 × 10⁷ kg
D. 48 × 10 ⁷ kg
Correct Answer: B
Rationale: Scientific notation requires a coefficient between 1 and 10 multiplied by 10 raised to an integer power.
Moving the decimal 6 places to the right gives 4.8, so the exponent is -6: 4.8 × 10 ⁶ kg. Option A uses a positive
exponent (would be a large number), C is off by one place, and D has a coefficient outside the 1-10 range. PHY 111
students must handle scientific notation fluently when working with very small or very large physical quantities.
Q9: A chemistry calculation requires multiplying (2.0 × 10⁴) by (3.0 × 10 ²). The correctly expressed
result is:
A. 6.0 × 10⁴
B. 6.0 × 10² *[CORRECT]*
C. 6.0 × 10⁷²
D. 6.0 × 10⁶
Correct Answer: B
Rationale: When multiplying numbers in scientific notation, multiply the coefficients and add the exponents:
(2.0)(3.0) = 6.0, and 4 + (-2) = 2, giving 6.0 × 10². Option A forgot to add the negative exponent, C subtracted
instead of adding, and D combined errors. This skill is essential for physics calculations involving very small and
very large quantities simultaneously.
RIO SALADO PHY 111 - Midterm 1 (2026/2027) | Page 4
PHY 111 — Introductory Physics
MIDTERM 1
Questions with Complete Solutions
Edition
Total Questions 100
Sections 7
Format Multiple Choice (A-D)
Cognitive Distribution 25% Recall | 50% Application | 25% Analysis
Style 70% Scenario-Based | 30% Direct Knowledge
Aligned With Rio Salado PHY 111 Syllabus; AAAS Vision & Change;
Introductory Physics Curriculum Standards (2026/2027)
Special Inclusions 25 Calculation | 15 Vector Resolution | 10 Graph Reasoning
Each question includes the correct answer and a 2-4 sentence rationale grounded in the Rio Salado
PHY 111 curriculum and standard physics problem-solving methodology.
, Section 1: Measurement, Units, & Scientific Notation
12 Questions | Cognitive levels: Recall, Application, Analysis
Q1: A student is calibrating a laboratory balance for a Rio Salado PHY 111 density lab. Which of the
following lists ONLY SI base units (fundamental quantities), as defined by the International System of
Units?
A. meter, kilogram, second, liter
B. meter, kilogram, second, newton
C. meter, kilogram, second, ampere, kelvin, mole, candela *[CORRECT]*
D. kilogram, second, kelvin, watt
Correct Answer: C
Rationale: The seven SI base units are meter (length), kilogram (mass), second (time), ampere (electric current),
kelvin (temperature), mole (amount of substance), and candela (luminous intensity). Liter (A) is a non-SI unit of
volume, newton (B) is a derived unit of force (kg·m/s²), and watt (D) is a derived unit of power. The Rio Salado PHY
111 curriculum emphasizes distinguishing base quantities from derived quantities as the foundation of dimensional
analysis.
Q2: In a workplace scenario, an engineer must convert a pressure reading. Which of the following is a
DERIVED unit (constructed from base units) rather than a base unit?
A. kilogram
B. newton *[CORRECT]*
C. second
D. kelvin
Correct Answer: B
Rationale: The newton is a derived unit defined as kg·m/s² (from F = ma). Kilogram (mass), second (time), and
kelvin (temperature) are all SI base units. The PHY 111 methodology requires students to express derived units in
terms of base units to verify dimensional consistency in formulas such as P = F/A.
Q3: A biologist measures a cell diameter of 25 μm (micrometers). To enter this value into a statistics
spreadsheet using millimeters, the correct conversion is:
A. 0.025 mm *[CORRECT]*
B. 0.25 mm
C. 2.5 mm
D. 0.0025 mm
Correct Answer: A
Rationale: The prefix micro (μ) equals 10 ⁶ and milli equals 10 ³. Therefore 25 μm = 25 × 10 ⁶ m = 0.025 ×
10 ³ m = 0.025 mm. Option B errors by a factor of 10, C by a factor of 100, and D by a factor of 10 in the opposite
direction. Mastering metric prefix conversion is essential for accurate scientific communication in PHY 111
laboratory work.
RIO SALADO PHY 111 - Midterm 1 (2026/2027) | Page 2
,Q4: A computer chip feature is advertised as 14 nm (nanometers). Expressed in meters using scientific
notation, this dimension equals:
A. 1.4 × 10 ⁹m
B. 1.4 × 10 ⁸ m *[CORRECT]*
C. 1.4 × 10 ⁷m
D. 1.4 × 10 ⁶m
Correct Answer: B
Rationale: The prefix nano (n) equals 10 ⁹, so 14 nm = 14 × 10 ⁹ m = 1.4 × 10 ⁸ m (the decimal is shifted one
place left, increasing the exponent by 1). Option A keeps the original coefficient, while C and D shift the decimal in
the wrong direction. PHY 111 students must be fluent in converting between metric prefixes and scientific notation.
Q5: A student derives a formula for speed v in terms of distance d and time t. Which equation is
dimensionally consistent?
A. v = d × t
B. v = d / t²
C. v = d / t *[CORRECT]*
D. v = t / d
Correct Answer: C
Rationale: Speed has units of [length]/[time]. In option C, d/t gives (m)/(s) = m/s, which matches. Option A gives
m·s (wrong), B gives m/s² (acceleration units), and D gives s/m (inverse speed). Dimensional analysis is a critical
PHY 111 problem-solving tool for catching algebraic errors before numerical substitution.
Q6: A field researcher records three measurements of a sample length: 12.4 cm, 12.37 cm, and 12.41 cm.
Reported with the correct number of significant figures, the sum equals:
A. 37.18 cm
B. 37.2 cm *[CORRECT]*
C. 37 cm
D. 37.180 cm
Correct Answer: B
Rationale: For addition/subtraction, the result is rounded to the same number of DECIMAL PLACES as the
measurement with the fewest decimal places. Here 12.4 cm has one decimal place, so the sum 37.18 cm rounds to
37.2 cm. Option A keeps extra digits, C rounds too aggressively, and D adds false precision. PHY 111 sig-fig rules
prevent over-reporting precision that the instruments cannot support.
RIO SALADO PHY 111 - Midterm 1 (2026/2027) | Page 3
, Q7: In a projectile calculation, a student multiplies 3.50 m by 2.1 s. The product, reported with the
correct number of significant figures, is:
A. 7.350 m·s
B. 7.35 m·s
C. 7.4 m·s *[CORRECT]*
D. 7 m·s
Correct Answer: C
Rationale: For multiplication/division, the result has the same number of significant figures as the factor with the
fewest sig figs. 3.50 has 3 sig figs; 2.1 has 2 sig figs. Therefore the product 7.35 must round to 2 sig figs: 7.4 m·s.
Option B incorrectly preserves 3 sig figs, A preserves 4, and D rounds to 1. PHY 111 stresses that sig figs
communicate measurement precision, not arbitrary decimal places.
Q8: The mass of a dust particle is measured as 0.0000048 kg. In correct scientific notation, this value is
written as:
A. 4.8 × 10ⁿ kg
B. 4.8 × 10 ⁶ kg *[CORRECT]*
C. 4.8 × 10⁷ kg
D. 48 × 10 ⁷ kg
Correct Answer: B
Rationale: Scientific notation requires a coefficient between 1 and 10 multiplied by 10 raised to an integer power.
Moving the decimal 6 places to the right gives 4.8, so the exponent is -6: 4.8 × 10 ⁶ kg. Option A uses a positive
exponent (would be a large number), C is off by one place, and D has a coefficient outside the 1-10 range. PHY 111
students must handle scientific notation fluently when working with very small or very large physical quantities.
Q9: A chemistry calculation requires multiplying (2.0 × 10⁴) by (3.0 × 10 ²). The correctly expressed
result is:
A. 6.0 × 10⁴
B. 6.0 × 10² *[CORRECT]*
C. 6.0 × 10⁷²
D. 6.0 × 10⁶
Correct Answer: B
Rationale: When multiplying numbers in scientific notation, multiply the coefficients and add the exponents:
(2.0)(3.0) = 6.0, and 4 + (-2) = 2, giving 6.0 × 10². Option A forgot to add the negative exponent, C subtracted
instead of adding, and D combined errors. This skill is essential for physics calculations involving very small and
very large quantities simultaneously.
RIO SALADO PHY 111 - Midterm 1 (2026/2027) | Page 4
