Diagnostic Test: Mechanics

10 multiple-choice questions covering classical mechanics. Select the best answer for each question, then check your score using the answer key below.

Question 1. A car accelerates uniformly from rest to 30 m/s in 10 seconds. What is its acceleration?

(A) 0.33 m/s^2 (B) 3.0 m/s^2 (C) 30 m/s^2 (D) 300 m/s^2

Question 2. According to Newton’s second law, if you double the force applied to an object while keeping its mass constant, the acceleration:

(A) Doubles (B) Halves (C) Stays the same (D) Quadruples

Question 3. A 5 kg object is lifted 4 meters at constant velocity. What is the work done against gravity? (Take g = 10 m/s^2)

(A) 12.5 J (B) 50 J (C) 200 J (D) 400 J

Question 4. What is the SI unit of impulse?

(A) Newton (N) (B) Joule (J) (C) Newton-second (Ns) (D) Kilogram-meter per second (kg*m/s)

Question 5. In a perfectly inelastic collision between two objects:

(A) Both momentum and kinetic energy are conserved (B) Only momentum is conserved (C) Neither momentum nor kinetic energy is conserved (D) Only kinetic energy is conserved

Question 6. The moment of inertia of an object depends on:

(A) Only its mass (B) Its mass and how that mass is distributed relative to the axis of rotation (C) Only the axis of rotation (D) The angular velocity of the object

Question 7. A simple pendulum has a period T. If the length of the pendulum is quadrupled, the new period is:

(A) T/2 (B) T (C) 2T (D) 4T

Question 8. At the top of its trajectory (maximum height), a projectile launched at an angle has:

(A) Zero velocity and zero acceleration (B) Zero velocity and acceleration g downward (C) Horizontal velocity only and acceleration g downward (D) Vertical velocity only and zero acceleration

Question 9. The work-energy theorem states that:

(A) Work done equals the change in kinetic energy (B) Work done equals the change in potential energy (C) Kinetic energy is always conserved (D) Potential energy is always conserved

Question 10. A disk and a solid sphere of equal mass and radius roll down an incline from the same height. Which reaches the bottom first?

(A) They reach the bottom at the same time (B) The disk (C) The sphere (D) the answer varies based on on the mass

Checking your mechanics foundations: Diagnostic tests quickly reveal which concepts you have mastered and which need more work. They are like a health check for your physics understanding.

Why it matters: Classical mechanics is the foundation of all physics, gaps in your understanding will propagate to electromagnetism, quantum mechanics, and beyond.

The key insight: If you cannot draw a free body diagram and apply F=ma, you do not truly understand mechanics, use diagnostic tests as a starting point for deeper study, not as an endpoint.

Scoring: Count your correct answers out of 10. A score of 8 or above indicates strong mastery of classical mechanics. Review the explanations in the practice problems for any questions you answered incorrectly.

Confusing inertial and non-inertial reference frames: Newton’s laws only hold in inertial frames. In accelerating frames, fictitious forces (Coriolis, centrifugal) must be added manually.

Forgetting that acceleration is the second derivative of position: Many students use v = at for non-constant acceleration. Only valid for constant acceleration; otherwise use calculus.

Neglecting that momentum is conserved only when net external force is zero: Internal forces cancel by Newton’s third law, but external forces change total momentum. Always check the system boundary.

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