H2 Physics Flashcards

A ball is thrown horizontally from a height of 20m. Taking g = 10 m/s², how long does it take to reach the ground?

Answer: 2s

Using h = ½gt²: 20 = ½×10×t². t² = 4. t = 2s. Horizontal motion is independent of vertical free fall.

What is the work-energy theorem?

Answer: The net work done on an object equals its change in kinetic energy

The work-energy theorem states that the net work done on an object equals its change in kinetic energy: W_net = ΔKE = ½mv² - ½mu².

State Newton's Third Law of Motion.

Answer: Every action has an equal and opposite reaction acting on different objects

Newton's Third Law: for every action force, there is an equal and opposite reaction force, acting on DIFFERENT objects. The forces are equal in magnitude but act on different bodies.

A spring with spring constant k = 200 N/m is compressed by 0.05 m. What is the elastic potential energy stored?

Answer: 0.25 J

E = ½kx² = ½ × 200 × (0.05)² = 100 × 0.0025 = 0.25 J.

What is the principle of superposition of waves?

Answer: When two waves meet, the resultant displacement is the vector sum of individual displacements

The principle of superposition states that when two or more waves overlap, the resultant displacement at any point is the algebraic (vector) sum of the individual displacements.

What is meant by 'terminal velocity'?

Answer: The constant velocity reached when drag force equals driving force (or weight)

Terminal velocity is the constant velocity reached by a falling object when the upward drag force equals the downward weight, so net force = 0 and acceleration = 0.