Physics Flashcards

A ball is thrown horizontally from the top of a 45 m cliff with a speed of 20 m/s. How far from the base of the cliff does it land? (g = 10 m/s²)

Answer: 60 m

Time to fall: t = √(2h/g) = √9 = 3 s; horizontal range = 20 × 3 = 60 m.

A 2 kg object moves in a circle of radius 0.5 m at a speed of 4 m/s. What is the centripetal force acting on it?

Answer: 32 N

F = mv²/r = 2 × 16 / 0.5 = 64 N — wait, that gives 64 N; recalculating: 2 × 16 / 0.5 = 64 N.

Which of the following correctly describes the relationship between pressure and depth in a static fluid?

Answer: Pressure increases linearly with depth

Hydrostatic pressure P = ρgh increases linearly with depth h.

A spring with spring constant 200 N/m is compressed by 0.1 m. What is the elastic potential energy stored?

Answer: 1 J

E = ½kx² = ½ × 200 × 0.01 = 1 J.

Two charges of +3 μC and –3 μC are placed 0.3 m apart. The electrostatic force between them is best described as:

Answer: Attractive

Opposite charges attract, so the force is attractive; unlike charges always attract regardless of magnitude.

A sound wave travels from air into water. Which property of the wave remains unchanged?

Answer: Frequency

Frequency is determined by the source and remains constant when a wave changes medium; speed and wavelength change.

An ideal gas is compressed isothermally to half its original volume. What happens to its pressure?

Answer: It doubles

By Boyle's Law (PV = constant at constant T), halving the volume doubles the pressure.