IIT JEE Physics

Solve 30 IIT JEE Physics Mechanics questions with answers, explanations, and instant scoring. Attempt all 30 questions. Each carries 4 marks. No negative marking. Q1. A particle moves with constant acceleration. Ratio of velocities in 1s and 2s? 1 : 2 1 : 4 2 : 1 4 : 1 Q2. Work done by gravity in a closed path is: Zero Positive Negative Infinite Q3. Dimensions of force are: MLT⁻² ML²T⁻² M²LT⁻² ML⁻¹T⁻² Q4. Angle for maximum range of projectile is: 45° 30° 60° 90° Q5. Kinetic energy is proportional to: v v² v³ 1/v Q6. Acceleration at highest point of projectile: 0 g 2g -g Q7. SI unit of momentum: kg·m/s Newton Joule Watt Q8. If net force on body is zero, motion is: Rest Uniform motion Accelerated Random Q9. Escape velocity depends on: Mass Radius Both mass and radius None Q10. Work-energy theorem relates: Force Work & kinetic energy Momentum Velocity Submit IIT JEE Physics Notes – Mechanics (Practice Paper Part 1) Mechanics forms the backbone of IIT JEE Physics, and this quiz covers several fundamental concepts that every aspirant must master. These notes consolidate the key ideas, formulas, and conceptual clarity required to solve such questions effectively. 1. Kinematics and Motion Basics In problems involving constant acceleration, velocity changes linearly with time. The key equations are: If a particle starts from rest, velocity becomes directly proportional to time (v∝tv \propto tv∝t). That’s why velocity ratios often reduce to time ratios. Graphs are extremely important: Understanding graphical interpretation is crucial for JEE. 2. Projectile Motion Projectile motion is a combination of horizontal and vertical motion: Key formulas: Maximum range occurs at 45∘45^\circ45∘.At the highest point, velocity is horizontal but acceleration is still ggg downward — a very common conceptual trap. 3. Newton’s Laws of Motion Newton’s laws define how forces affect motion: If net force is zero, acceleration is zero — but velocity may not be zero. This means the object can still move with constant velocity. 4. Work, Energy, and Power Work is defined as:W=F⋅s⋅cos⁡θW = F \cdot s \cdot \cos\thetaW=F⋅s⋅cosθ Important cases: Kinetic Energy:KE=12mv2KE = \frac{1}{2}mv^2KE=21​mv2 Potential Energy:PE=mghPE = mghPE=mgh Work-Energy Theorem:W=ΔKEW = \Delta KEW=ΔKE Power:P=WtP = \frac{W}{t}P=tW​ These formulas are frequently used in JEE problems involving motion and forces. 5. Momentum and Impulse Momentum is defined as:p=mvp = mvp=mv Impulse:Impulse=F×t=ΔpImpulse = F \times t = \Delta pImpulse=F×t=Δp This concept is important in collision problems. If a large force acts for a short time, it can still produce significant change in momentum. 6. Collisions There are two main types: Perfectly inelastic collisions involve objects sticking together. Understanding conservation laws is key for solving collision-based numerical problems. 7. Circular Motion For a body moving in a circle: Centripetal force:F=mv2rF = \frac{mv^2}{r}F=rmv2​ Direction: Always towards the center. Angular velocity:ω=vr\omega = \frac{v}{r}ω=rv​ Unit: rad/s Important insight: Even if speed is constant, velocity changes due to direction — hence acceleration exists. 8. Gravitation Gravitational force:F=GMmr2F = \frac{GMm}{r^2}F=r2GMm​ Acceleration due to gravity:g=GMR2g = \frac{GM}{R^2}g=R2GM​ If radius increases, gravity decreases (inverse square relationship). Escape velocity:ve=2GMRv_e = \sqrt{\frac{2GM}{R}}ve​=R2GM​​ It depends on both mass and radius of the planet. 9. Friction Frictional force:f=μNf = \mu Nf=μN Depends on: It does NOT depend on surface area directly. Types: Static friction adjusts itself up to a maximum value. 10. Elasticity and Hooke’s Law Hooke’s Law:F=kxF = kxF=kx Valid only within elastic limit. Beyond elastic limit, permanent deformation occurs and the law is no longer valid. 11. Rotational Mechanics Torque:τ=r×F\tau = r \times Fτ=r×F Angular momentum:L=r×pL = r \times pL=r×p Conservation of angular momentum occurs when no external torque acts. 12. Important Conceptual Insights 13. Dimensional Analysis Used to check correctness of equations. Example:Force:[F]=MLT−2[F] = MLT^{-2}[F]=MLT−2 Energy:[ML2T−2][ML^2T^{-2}][ML2T−2] This helps eliminate wrong options in MCQs. Final Strategy for IIT JEE Mechanics questions in JEE often combine multiple concepts (e.g., energy + motion + force), so integrated understanding is essential.