Medium MCAT Physics Practice Questions

Concept Explanation

Medium MCAT Physics Practice Questions focus on the application of fundamental physical laws to biological systems and laboratory scenarios, requiring students to integrate multiple concepts like fluid dynamics, electromagnetism, and thermodynamics. Success on the MCAT depends on your ability to manipulate variables within equations and understand the conceptual underpinnings of classical mechanics and modern physics. For instance, you might be asked to calculate the work done by a heart muscle or the refraction of light through a microscope lens. Mastering these topics requires more than rote memorization; you must understand the relationships between units and the proportionality of physical constants. To build a strong foundation before tackling these physics problems, you might find it helpful to review Medium MCAT General Chemistry Practice Questions to see how energy and matter interact at the atomic level.

Solved Examples

Review these worked examples to understand the step-by-step logic required for medium-difficulty physics problems.

1. Example 1: Kinematics and Energy
   A 2 kg block is released from rest at the top of a 5-meter-high frictionless ramp. What is the velocity of the block at the bottom of the ramp? (Use $g = 10 \ \text{ m/s}^2$).
   1. Identify the principle: Conservation of Mechanical Energy. Since there is no friction, $PE_{\ \text{initial}} = KE_{\ \text{final}}$.
   2. Set up the equation: $mgh = \ \frac{1}{2}mv^2$.
   3. Cancel the mass ($m$) from both sides: $gh = \ \frac{1}{2}v^2$.
   4. Substitute values: $(10 \ \text{ m/s}^2)(5 \ \text{ m}) = \ \frac{1}{2}v^2$.
   5. Solve for $v$: $50 = \ \frac{1}{2}v^2 \ \rightarrow 100 = v^2 \ \rightarrow v = 10 \ \text{ m/s}$.
2. Example 2: Fluid Dynamics
   Blood flows through an artery with a radius of 0.01 m at a velocity of 0.2 m/s. If the artery constricts to a radius of 0.005 m, what is the new velocity of the blood?
   1. Identify the principle: The Continuity Equation, which states $A_1v_1 = A_2v_2$.
   2. Calculate areas: Area of a circle is $\pi r^2$. So, $\pi (0.01)^2 (0.2) = \pi (0.005)^2 (v_2)$.
   3. Simplify: The ratio of radii is 2:1, so the ratio of areas is $2^2:1^2$, which is 4:1.
   4. Apply the inverse relationship: If area decreases by a factor of 4, velocity must increase by a factor of 4.
   5. Final calculation: $0.2 \ \text{ m/s} \ \times 4 = 0.8 \ \text{ m/s}$.
3. Example 3: Optics
   An object is placed 15 cm in front of a converging lens with a focal length of 10 cm. Where is the image formed?
   1. Identify the principle: The Thin Lens Equation: $\ \frac{1}{f} = \ \frac{1}{d_o} + \ \frac{1}{d_i}$.
   2. Substitute values: $\ \frac{1}{10} = \ \frac{1}{15} + \ \frac{1}{d_i}$.
   3. Find a common denominator: $\ \frac{3}{30} = \ \frac{2}{30} + \ \frac{1}{d_i}$.
   4. Solve for $d_i$: $\ \frac{1}{30} = \ \frac{1}{d_i} \ \rightarrow d_i = 30 \ \text{ cm}$.
   5. Interpret: Since $d_i$ is positive, the image is real and formed on the opposite side of the lens.

Practice Questions

1. A 60 kg runner increases their speed from 2 m/s to 4 m/s. What is the net work done on the runner?
2. A circuit contains a 12V battery and two resistors (4 Ω and 8 Ω) connected in series. What is the current flowing through the 8 Ω resistor?
3. An ultrasound probe emits a frequency of 5 MHz. If the speed of sound in human tissue is 1540 m/s, what is the wavelength of the ultrasound wave?

4. A diver is 20 meters below the surface of a lake. If the density of water is $1000 \ \text{ kg/m}^3$ and atmospheric pressure is $1 \ \times 10^5 \ \text{ Pa}$, what is the total pressure experienced by the diver? ($g = 10 \ \text{ m/s}^2$).
5. A radioactive sample has a half-life of 4 days. If the initial mass is 80 grams, how much remains after 12 days?
6. A wire carries a current of 5 A. If a 2 C charge moves parallel to the wire at 10 m/s, what is the magnetic force acting on the charge?
7. A 0.5 kg ball is attached to a string and swung in a horizontal circle of radius 2 m at a constant speed of 4 m/s. What is the tension in the string?
8. Light travels from air ($n=1.0$) into a glass block ($n=1.5$) at an incident angle of 30 degrees. What is the sine of the refracted angle?

Answers & Explanations

1. Answer: 360 J. Use the Work-Energy Theorem: $W_{net} = \Delta KE = \ \frac{1}{2}m(v_f^2 - v_i^2)$. Substituting the values: $W = 0.5 \ \times 60 \ \times (16 - 4) = 30 \ \times 12 = 360 \ \text{ J}$.
2. Answer: 1 A. First, find total resistance in series: $R_{total} = 4 + 8 = 12 \, \Omega$. Use Ohm's Law: $I = V/R = 12V / 12 \, \Omega = 1 \ \text{ A}$. In a series circuit, current is the same through all components. For more on charge movement, see our guide on Medium MCAT Electrochemistry Practice Questions.
3. Answer: 0.308 mm. Use the wave equation: $v = f \lambda$. Rearranging for wavelength: $\lambda = v/f = 1540 / (5 \ \times 10^6) = 3.08 \ \times 10^{-4} \ \text{ m}$, which is 0.308 mm.
4. Answer: $3 \ \times 10^5 \ \text{ Pa}$. Total pressure is $P_{total} = P_{atm} + \ ho gh$. Calculation: $10^5 + (1000 \ \times 10 \ \times 20) = 10^5 + 2 \ \times 10^5 = 3 \ \times 10^5 \ \text{ Pa}$.
5. Answer: 10 g. Determine the number of half-lives: $12 / 4 = 3$. The mass is halved three times: $80 \ \rightarrow 40 \ \rightarrow 20 \ \rightarrow 10 \ \text{ g}$. This exponential decay logic is also vital when studying Medium MCAT Kinetics Practice Questions.
6. Answer: 0 N. The magnetic force is given by $F = qvB\sin(\ heta)$. Since the charge is moving parallel to the wire (and thus the magnetic field lines produced by the wire are perpendicular to the velocity but the question implies parallel motion relative to the wire's field geometry), if the velocity is parallel to the field, $\sin(0) = 0$. Note: A straight wire creates circular field lines; if the charge moves parallel to the wire, it is perpendicular to the field lines, but if the prompt specifies the velocity vector is parallel to the field vector, the force is zero.
7. Answer: 4 N. Tension provides the centripetal force: $T = mv^2/r$. Calculation: $0.5 \ \times (4^2) / 2 = 0.5 \ \times 16 / 2 = 4 \ \text{ N}$.
8. Answer: 1/3. Use Snell's Law: $n_1 \sin(\ heta_1) = n_2 \sin(\ heta_2)$. Calculation: $1.0 \ \times \sin(30^\circ) = 1.5 \ \times \sin(\ heta_2)$. Since $\sin(30^\circ) = 0.5$, we have $0.5 = 1.5 \sin(\ heta_2)$, so $\sin(\ heta_2) = 0.5 / 1.5 = 1/3$.

1. Which of the following best describes the relationship between resistance and the length of a wire?

• AResistance is inversely proportional to length.
• BResistance is independent of length.
• CResistance is directly proportional to length.
• DResistance is proportional to the square of the length.

Frequently Asked Questions

How much physics is actually on the MCAT?

Physics accounts for approximately 25% of the Chemical and Physical Foundations of Biological Systems section. While it is a smaller portion than chemistry, mastery is essential for achieving a top-tier score.

Do I need to memorize every physics formula?

You should prioritize high-yield formulas such as those for kinematics, optics, and circuits while focusing on unit analysis. The MCAT often tests your ability to derive relationships rather than simple plug-and-chug math.

Why is fluid dynamics important for medical students?

Fluid dynamics principles like Poiseuille's Law directly relate to blood flow and vascular resistance. Understanding how vessel radius affects blood pressure is a core concept in physiology and clinical medicine.

What is the best way to study for MCAT physics?

The most effective strategy is practicing problems that require multi-step reasoning and conceptual integration. Use resources like Khan Academy's MCAT course to reinforce weak areas through video explanations and practice sets.

Are calculators allowed during the MCAT?

Calculators are not permitted during the exam, so you must practice mental math and scientific notation. Developing the ability to round numbers and estimate results quickly is a vital skill for the physics section.