Forces and Motion Flashcards
What is the difference between scalar and vector quantities?
Scalar has magnitude only (e.g., speed). Vector has magnitude AND direction (e.g., velocity).
What is velocity?
Speed in a specified direction (vector quantity).
What does the gradient of a distance-time graph represent?
Speed.
How is acceleration calculated? (No equation needed)
Change in velocity divided by time taken.
What does a horizontal line on a velocity-time graph show?
Constant velocity (zero acceleration).
State Newton’s First Law of Motion.
An object stays at rest/moves at constant velocity unless acted on by a resultant force.
What is inertia?
The resistance of an object to changes in its motion (depends on mass).
Define momentum.
Product of an object’s mass and velocity (vector quantity).
State the principle of conservation of momentum.
Total momentum before a collision/explosion = total momentum after (closed system).
What factors affect stopping distance?
Thinking distance + braking distance. Factors: speed, reaction time, vehicle condition (e.g., brakes), road conditions (e.g., ice).
How does mass affect acceleration (for a fixed force)?
Higher mass = lower acceleration (F=ma; mass and acceleration inversely related).
What is work done?
Energy transferred when a force moves an object (work done = force × distance moved).
What is Hooke’s Law?
Extension of a spring is directly proportional to force applied (up to limit of proportionality).
What happens if a spring is stretched beyond its elastic limit?
Permanent deformation (plastic behavior; won’t return to original length).
What does the gradient of a force-extension graph represent?
Spring constant (stiffness; steeper gradient = stiffer spring).
What is pressure in fluids?
Force per unit area (p = F/A). Increases with depth and fluid density.
Why does atmospheric pressure decrease at higher altitudes?
Less air above = smaller weight of air molecules exerting force.
What is gravitational field strength?
Force per unit mass experienced by an object in a gravitational field (N/kg).
What is the difference between mass and weight?
Mass = scalar (amount of matter). Weight = force from gravity (vector; W=mg).
What is resultant force?
Single force representing the vector sum of all forces acting on an object.
What is terminal velocity?
Constant speed when drag force = weight (resultant force = 0). E.g., skydiver.
What increases thinking distance?
Higher speed, distractions, tiredness, alcohol/drugs, poor visibility.
What increases braking distance?
Higher speed, worn brakes/tyres, icy/wet roads, increased vehicle mass.
How does reaction time affect stopping distance?
Longer reaction time = greater thinking distance (driver delays braking).
