MotionCambridge IGCSE Physics: Flashcards

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Define speed and state the equation that relates speed, distance and time.

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Define speed and state the equation that relates speed, distance and time.: Speed is the distance travelled per unit time. The equation is: v = s/t, where v is speed (m/s), s is distance (m), and t is time (s).
What is the difference between speed and velocity?: Speed is the distance travelled per unit time (scalar quantity). Velocity is speed in a given direction (vector quantity). Velocity includes both magnitude and direction.
State the equation for calculating average speed.: Average speed = total distance travelled / total time taken
How can you determine speed from a distance–time graph?: Speed is calculated from the gradient (slope) of a straight-line section on a distance–time graph. Gradient = change in distance / change in time = speed.
What information can be obtained from interpreting a distance–time graph?: A distance–time graph shows whether an object is: at rest (horizontal line), moving with constant speed (straight sloped line), or accelerating/decelerating (curved line).
Define acceleration and state the equation used to calculate it.: Acceleration is the change in velocity per unit time. The equation is: a = Δv/Δt, where a is acceleration (m/s²), Δv is change in velocity (m/s), and Δt is change in time (s).
How is acceleration determined from a speed–time graph?: Acceleration is calculated from the gradient (slope) of a speed–time graph. Gradient = change in velocity / change in time = acceleration.
What does a horizontal line on a speed–time graph indicate?: A horizontal line on a speed–time graph indicates constant speed (zero acceleration).
What does a curved line on a speed–time graph indicate?: A curved line on a speed–time graph indicates changing acceleration (non-uniform acceleration).
What is deceleration and how is it represented in calculations?: Deceleration is a negative acceleration (a decrease in velocity). It is represented as a negative value in calculations using a = Δv/Δt.
State the value of gravitational field strength near the Earth's surface.: The acceleration due to free fall near the Earth's surface, g, is approximately 9.8 m/s² (or 10 m/s² for estimates).
How does air resistance affect the motion of a falling object?: Air resistance opposes the motion of a falling object. Initially, the object accelerates due to gravity, but as speed increases, air resistance increases, reducing acceleration until terminal velocity is reached.
Define terminal velocity and explain when it is reached.: Terminal velocity is the maximum constant velocity reached by a falling object when the resistive forces (air or liquid resistance) equal the gravitational force, resulting in zero acceleration.
Describe the motion of an object falling without air resistance.: An object falling without air resistance undergoes constant acceleration equal to g (9.8 m/s²). It continuously accelerates throughout its fall.
How can the distance travelled be determined from a speed–time graph?: The distance travelled equals the area under a speed–time graph. For constant speed, area = speed × time. For constant acceleration, area = ½ × base × height.