Govt. Exams
Entrance Exams
This problem requires using Newton's Second Law to find acceleration, then applying kinematic equations to determine final velocity.
Step 1: Find the Acceleration Using Newton's Second Law
Newton's Second Law states that the net force equals mass times acceleration. We need to rearrange to solve for acceleration.
Step 2: Apply the Kinematic Equation to Find Final Velocity
Since the object starts from rest (initial velocity = 0) and travels a distance of 5 m with constant acceleration, we use the equation that relates velocity, acceleration, and distance.
The velocity after traveling 5 m is 5√2 m/s (≈ 7.07 m/s). The answer is (A).
The Lyman series involves transitions to n=1 from higher energy levels. Balmer series ends at n=2, Paschen at n=3, and Brackett at n=4.
Acoustic impedance (Z) = ρ × c, where ρ is density and c is sound velocity. SI unit is kg/(m²·s). It's crucial for understanding sound reflection and transmission.
# Photoelectric Effect - Maximum Kinetic Energy
The photoelectric effect describes how photons transfer their energy to electrons in a metal, with excess energy becoming kinetic energy after overcoming the work function barrier.
Step 1: Calculate the Energy of the Incident Photon
The energy of a photon is determined by its frequency using Planck's equation.
Step 2: Convert Photon Energy to eV
Convert joules to electron volts using the given conversion factor.
Step 3: Apply Einstein's Photoelectric Equation
The maximum kinetic energy equals the photon energy minus the work function (threshold energy).
The maximum kinetic energy of the photoelectron is 0.07 eV.
Answer: (A) 0.07 eV
From orbital mechanics: v = √(GM/r). If r becomes 2r, then v_new = √(GM/2r) = v/√2. Velocity decreases by factor √2.
Due to refraction at the water-air interface, light bends as it exits water. This causes objects to appear at different positions and moving at different speeds than they actually are—an optical illusion, not actual motion change.
Period T = 2π√(m/k) = 2π√(5/200) = 2π√(1/40) = 2π × (1/(2√10)) = π/√10 ≈ π s (approximately).
Young's modulus is a material property independent of the wire's dimensions or elastic deformation state. It depends only on the material composition and atomic structure, not on physical changes.
At critical angle θ_c, refracted ray becomes parallel to the interface. Beyond this angle, no refraction occurs; light completely reflects back into the denser medium (total internal reflection). This principle enables fiber optics.
Carnot efficiency: η = 1 - (T_cold/T_hot) = 1 - (300/400) = 1 - 0.75 = 0.25 = 25%. This is the theoretical maximum for any heat engine.
