Physics
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Distance
The full length covered to reach a certain point
Displacement
How far an object has shifted from a certain point
Speed
how quickly an object moves over distance (distance/time)
Average Speed
Total distance over the the total time
Instantaneous Speed
A measurement of how fast an object was moving at one particular moment
Scalar
Quantities that can be described by a by a magnitude or numerical value alone Examples: Time, speed, mass, distance
Vector
Quantities are described by both magnitude and direction. Examples: force, displacement, acceleration, velocity
Acceleration
Rate at which velocity changes with time in terms of speed and direction (A = v/t)
Velocity
The speed of something in a given direction
Ways of measuring speed
Speedometer, ticker timer, radar gun
Speedometer
Displays instantaneous speed of a vehicle by using sensors to measure wheel rotation and tire circumference
Ticker Timer
Measures speed of an object that marks time by making dots on a strip of paper
Radar Gun
Detects reflection of waves off the object
Driving Speed Impact on road safety
Faster speed = longer stop time = longer distance before stop = increased risk of crash
Reaction time
Time it takes for a driver to recognise a hazard. Affects alertness, fatigue Short reaction times = reduced crash likelihood
Reaction Distance
The distance a vehicle travels during the reaction time
How do mobile speed cameras work?
Detects waves that bounce off vehicles - speed measured based on time to return waves. Lidar uses laser beams
Piezoelectric Sensors
Works with other sensors embedded in the roads to detect pressure exerted and estimate speed
What are some factors that affect traffic accidents?
Speed, driver behaviour, road conditions, vehicle condition
What are some factors that affect stopping distance?
Speed, driver behaviour, road conditions, vehicle condition, reaction time
What forces act on falling objects and how do they relate to terminal velocity?
Gravity and air resistance Gravity accelerates downwards - air resistance builds up - eventually air resistance equals force of gravity and object stops accelerating and reaches a state called TERMINAL VELOCITY
Formulas for motion
v = u + at s = ut + 1/2at^2 v^2 = u^2 +2as
Net Force
Total force acting on an object after all the individual forces are combined.
1st law
An object will stay at rest and an object in motion will stay in motion unless acted upon by an external force