Physics Flashcards

A body moves in a circle of radius R with uniform speed v. What is the magnitude of the change in velocity when the body completes a quarter circle?

Answer: v√2

When the body completes a quarter circle, the angle between initial and final velocity vectors is 90°, so |Δv| = √(v²+v²) = v√2.

A spring of spring constant k is cut into two equal halves. The spring constant of each half is:

Answer: 2k

Spring constant is inversely proportional to length, so cutting the spring in half doubles the spring constant of each piece to 2k.

Which of the following correctly describes the work done by a conservative force in a closed path?

Answer: Always zero

A defining property of conservative forces is that the work done along any closed path is always zero.

Two blocks of masses 3 kg and 5 kg are connected by a string over a frictionless pulley. What is the acceleration of the system?

Answer: 2.45 m/s²

For an Atwood machine, a = (m₂−m₁)g/(m₁+m₂) = (5−3)×9.8/(3+5) = 2.45 m/s².

The dimensional formula for coefficient of viscosity (η) is:

Answer: [ML⁻¹T⁻¹]

From Newton's law of viscosity F = ηA(dv/dx), solving for η gives dimensions [ML⁻¹T⁻¹].

A particle undergoes simple harmonic motion with amplitude A and angular frequency ω. The maximum acceleration of the particle is:

Answer: ω²A

The acceleration in SHM is a = −ω²x, which is maximum when displacement x equals amplitude A, giving |a_max| = ω²A.

What happens to the time period of a simple pendulum when it is taken from the Earth's surface to the Moon's surface?

Answer: Increases

The Moon's gravitational acceleration is about 1/6 of Earth's, so T = 2π√(L/g) increases since g decreases.