Physics: Classical Mechanics & Kinematics Flashcards

A projectile is launched at 30° above the horizontal with an initial speed of 20 m/s. What is the maximum height reached? (g = 10 m/s²)

Answer: 5 m

The vertical component is 20sin(30°) = 10 m/s; max height = v²/(2g) = 100/20 = 5 m.

A 5 kg block slides down a frictionless incline of angle 37°. What is the block's acceleration? (g = 10 m/s², sin37° ≈ 0.6)

Answer: 6 m/s²

On a frictionless incline, a = g·sinθ = 10 × 0.6 = 6 m/s².

Two objects with masses 2 kg and 4 kg experience the same net force. What is the ratio of their accelerations (a₂ kg / a₄ kg)?

Answer: 2:1

From F = ma, acceleration is inversely proportional to mass, so a₂/a₄ = m₄/m₂ = 4/2 = 2:1.

A car traveling at 20 m/s decelerates uniformly and stops in 4 seconds. What distance does it travel while stopping?

Answer: 40 m

Using d = (v₀ + v)/2 × t = (20 + 0)/2 × 4 = 40 m.

Which of the following correctly describes the velocity of an object in uniform circular motion?

Answer: Constant in magnitude, changing in direction

In uniform circular motion, speed (magnitude of velocity) is constant but direction continuously changes.

A 10 kg box is pushed across a floor with a coefficient of kinetic friction μₖ = 0.3. What friction force acts on the box? (g = 10 m/s²)

Answer: 30 N

f_k = μₖ × N = μₖ × mg = 0.3 × 10 × 10 = 30 N.

An object is thrown vertically upward. At its peak, which statement is true?

Answer: Velocity is zero and acceleration is g downward

At the peak, velocity momentarily equals zero, but gravitational acceleration (g ≈ 9.8 m/s² downward) acts throughout the flight.