The Ultimate PHY 111 Midterm Mastery
Guide: 100 Essential Questions & Rationales
(2026-2027)*
### Section 1: Units, Measurement, & Vectors (Q1 - Q10)
**Q1:** What are the base SI units for length, mass, and time?
**A1:** Meter (m), Kilogram (kg), Second (s).
**Rationale:** These are the fundamental dimensions upon which mechanics is built. All other
mechanical units (like Newton or Joule) are derived from these three.
**Q2:** Convert 65 miles per hour to meters per second. (1 mile = 1609 m)
**A2:** 29.1 m/s. (65 * )
**Rationale:** Dimensional analysis requires converting miles to meters (numerator) and hours to
seconds (denominator). 1 hour = 3600 seconds.
**Q3:** Which of the following is a vector quantity: Speed, Distance, Velocity, or Mass?
**A3:** Velocity.
**Rationale:** Vectors require both magnitude and direction. Speed, distance, and mass are scalars
(magnitude only).
**Q4:** You walk 3 km East and then 4 km North. What is the magnitude of your resultant
displacement?
**A4:** 5 km.
**Rationale:** The vectors are perpendicular. Use the Pythagorean theorem: R = √(3² + 4²) = 5 km.
**Q5:** What is the direction (angle) of the resultant displacement described in Q4, measured from
East?
**A5:** 53.1° North of East. (θ = tan⁻¹(4/3))
,**Rationale:** The angle is found using inverse tangent (opposite/adjacent). Since North is "up" and
East is "right," the angle is above the East axis.
**Q6:** Given vector A = (5i + 5j) m, what is its magnitude?
**A6:** 7.07 m.
**Rationale:** Magnitude |A| = √(Ax² + Ay²) = √(25 + 25) = √50 ≈ 7.07 m.
**Q7:** What is a "scalar" quantity?
**A7:** A quantity fully described by a magnitude (number) alone (e.g., temperature, mass, time).
**Rationale:** Unlike vectors, scalars do not involve direction, making addition simpler (standard
algebra, not trigonometry).
**Q8:** Add vector A (10 m, East) and Vector B (10 m, West). What is the resultant?
**A8:** 0 m.
**Rationale:** They are antiparallel. 10m + (-10m) = 0m. This represents a net displacement of zero.
**Q9:** If a car travels around a circular track and returns to its starting point, what is its average
velocity?
**A9:** 0 m/s.
**Rationale:** Average velocity is total displacement divided by time. Since the displacement
(change in position) is zero, the velocity is zero, regardless of the distance traveled.
**Q10:** What is the order of magnitude of the mass of a car (approximately 1500 kg)?
**A10:** 10³ kg.
**Rationale:** 1500 is closer to 1000 (10³) than to 10,000 (10⁴). Estimating orders of magnitude
helps check if physics answers are reasonable.
---
### Section 2: Kinematics in One Dimension (Q11 - Q30)
**Q11:** Define average velocity.
**A11:** Displacement (Δx) divided by the time interval (Δt).
, **Rationale:** Average velocity is a vector. It depends on *net change* in position, not the total
path length.
**Q12:** A car accelerates from rest to 20 m/s in 5 seconds. What is its acceleration?
**A12:** 4 m/s².
**Rationale:** a = (Vf - Vi) / t = (20 - 0) / 5 = 4 m/s².
**Q13:** An object is thrown straight up. At the very top of its path, what is its velocity and
acceleration (assuming g = 9.8 m/s²)?
**A13:** Velocity = 0 m/s; Acceleration = 9.8 m/s² downward.
**Rationale:** The velocity is zero at the instantaneous turning point. However, gravity is still acting,
so acceleration remains constant at -9.8 m/s² (downward).
**Q14:** Write the kinematic equation that relates final velocity, initial velocity, acceleration, and
displacement (no time).
**A14:** Vf² = Vi² + 2aΔx.
**Rationale:** This equation is derived by eliminating "t" from the standard velocity and position
equations. It is very useful when time is not given.
**Q15:** A ball is dropped from a cliff. How far does it fall in 3 seconds? (Ignore air resistance, g = 10
m/s²)
**A15:** 45 m.
**Rationale:** Use Δy = Vi*t + 0.5*g*t². Since Vi = 0, Δy = 0.5 * 10 * 9 = 45 m.
**Q16:** What does the slope of a Position vs. Time graph represent?
**A16:** Velocity.
**Rationale:** Slope is rise over run (Δy/Δx). In physics, ΔPosition/ΔTime = Velocity.
**Q17:** What does the slope of a Velocity vs. Time graph represent?
**A17:** Acceleration.
**Rationale:** Slope is Δv/Δt, which is the definition of acceleration.
**Q18:** What does the area under a Velocity vs. Time graph represent?
Guide: 100 Essential Questions & Rationales
(2026-2027)*
### Section 1: Units, Measurement, & Vectors (Q1 - Q10)
**Q1:** What are the base SI units for length, mass, and time?
**A1:** Meter (m), Kilogram (kg), Second (s).
**Rationale:** These are the fundamental dimensions upon which mechanics is built. All other
mechanical units (like Newton or Joule) are derived from these three.
**Q2:** Convert 65 miles per hour to meters per second. (1 mile = 1609 m)
**A2:** 29.1 m/s. (65 * )
**Rationale:** Dimensional analysis requires converting miles to meters (numerator) and hours to
seconds (denominator). 1 hour = 3600 seconds.
**Q3:** Which of the following is a vector quantity: Speed, Distance, Velocity, or Mass?
**A3:** Velocity.
**Rationale:** Vectors require both magnitude and direction. Speed, distance, and mass are scalars
(magnitude only).
**Q4:** You walk 3 km East and then 4 km North. What is the magnitude of your resultant
displacement?
**A4:** 5 km.
**Rationale:** The vectors are perpendicular. Use the Pythagorean theorem: R = √(3² + 4²) = 5 km.
**Q5:** What is the direction (angle) of the resultant displacement described in Q4, measured from
East?
**A5:** 53.1° North of East. (θ = tan⁻¹(4/3))
,**Rationale:** The angle is found using inverse tangent (opposite/adjacent). Since North is "up" and
East is "right," the angle is above the East axis.
**Q6:** Given vector A = (5i + 5j) m, what is its magnitude?
**A6:** 7.07 m.
**Rationale:** Magnitude |A| = √(Ax² + Ay²) = √(25 + 25) = √50 ≈ 7.07 m.
**Q7:** What is a "scalar" quantity?
**A7:** A quantity fully described by a magnitude (number) alone (e.g., temperature, mass, time).
**Rationale:** Unlike vectors, scalars do not involve direction, making addition simpler (standard
algebra, not trigonometry).
**Q8:** Add vector A (10 m, East) and Vector B (10 m, West). What is the resultant?
**A8:** 0 m.
**Rationale:** They are antiparallel. 10m + (-10m) = 0m. This represents a net displacement of zero.
**Q9:** If a car travels around a circular track and returns to its starting point, what is its average
velocity?
**A9:** 0 m/s.
**Rationale:** Average velocity is total displacement divided by time. Since the displacement
(change in position) is zero, the velocity is zero, regardless of the distance traveled.
**Q10:** What is the order of magnitude of the mass of a car (approximately 1500 kg)?
**A10:** 10³ kg.
**Rationale:** 1500 is closer to 1000 (10³) than to 10,000 (10⁴). Estimating orders of magnitude
helps check if physics answers are reasonable.
---
### Section 2: Kinematics in One Dimension (Q11 - Q30)
**Q11:** Define average velocity.
**A11:** Displacement (Δx) divided by the time interval (Δt).
, **Rationale:** Average velocity is a vector. It depends on *net change* in position, not the total
path length.
**Q12:** A car accelerates from rest to 20 m/s in 5 seconds. What is its acceleration?
**A12:** 4 m/s².
**Rationale:** a = (Vf - Vi) / t = (20 - 0) / 5 = 4 m/s².
**Q13:** An object is thrown straight up. At the very top of its path, what is its velocity and
acceleration (assuming g = 9.8 m/s²)?
**A13:** Velocity = 0 m/s; Acceleration = 9.8 m/s² downward.
**Rationale:** The velocity is zero at the instantaneous turning point. However, gravity is still acting,
so acceleration remains constant at -9.8 m/s² (downward).
**Q14:** Write the kinematic equation that relates final velocity, initial velocity, acceleration, and
displacement (no time).
**A14:** Vf² = Vi² + 2aΔx.
**Rationale:** This equation is derived by eliminating "t" from the standard velocity and position
equations. It is very useful when time is not given.
**Q15:** A ball is dropped from a cliff. How far does it fall in 3 seconds? (Ignore air resistance, g = 10
m/s²)
**A15:** 45 m.
**Rationale:** Use Δy = Vi*t + 0.5*g*t². Since Vi = 0, Δy = 0.5 * 10 * 9 = 45 m.
**Q16:** What does the slope of a Position vs. Time graph represent?
**A16:** Velocity.
**Rationale:** Slope is rise over run (Δy/Δx). In physics, ΔPosition/ΔTime = Velocity.
**Q17:** What does the slope of a Velocity vs. Time graph represent?
**A17:** Acceleration.
**Rationale:** Slope is Δv/Δt, which is the definition of acceleration.
**Q18:** What does the area under a Velocity vs. Time graph represent?
