Physics: Motion, Forces, and the Solar System
Acceleration
Defined as change in velocity over time: .
Uniform acceleration indicates constant rate of change.
Key equation: , where v = final velocity, u = initial velocity, a = acceleration, s = distance.
Forces and Motion
Resultant force is necessary to change motion (Newton's First Law).
Newton's Second Law: (Force = mass x acceleration).
Newton's Third Law: Forces between two objects are equal and opposite.
Terminal Velocity
Occurs when forces (like drag) balance weight, establishing constant speed.
Drag increases with speed and depends on shape and area.
Example: Skydiver accelerates until drag equals weight, reaching terminal velocity.
In a vacuum, all objects fall at the same rate as there is no air resistance.
Stopping Distance
Total stopping distance = Thinking distance + Braking distance.
Influenced by speed, reaction time, road conditions, and brake quality.
Braking relies on friction and work done (energy transferred).
Reaction Times
Vary between individuals, affected by factors like fatigue and distractions.
Measured by catching a dropped ruler, with distance fallen indicating reaction time.
Investigating Motion
Set up experiments using a trolley, light gate, and pulley to measure acceleration.
Record effects of mass on acceleration; average results for accuracy.
Momentum
Defined as momentum = mass x velocity, a vector quantity (direction matters).
Total momentum before and after collision remains constant (Law of conservation of momentum).
A force acting on an object can change its momentum. Force can be calculated by: (change in momentum over time).