Describe how motion can be described.
Motion can be described in terms of position, speed or location.
Define distance and displacement.
Distance: the length of a path.
Displacement: the linear distance between the initial/final position of an object.
Describe reaction time/distance.
The time elapsed/distance travelled between a stimulus and a response.
Typically 1 second.
Describe factors that affect reaction time.
- Factors that affect bodily operation:
- vehicle speed
- driver fatigue
- drugs and alcohol
- distraction
Describe braking time/distance
The time elapsed/distance travelled after the brakes are applied for a vehicle to come to a full stop.
Describe factors that affect braking time.
- Factors that affect vehicle operation:
- vehicle speed
- road conditions (icy, wet, gravel)
- worn tyres.
Describe stopping distance.
The distance a vehicle travels between a stimulus and coming to a stop.
Stopping distance = reaction distance + braking distance.
Define speed and provide the formula for providing speed.
Speed is how quickly an object is able to move from one place to another.
Speed = distance / time
How to convert speed from km/h and m/s.
km/h / 3.6 = m/s
m/s x 3.6 = km/h
List some methods of measuring speed.
- ticker timers
- radar guns
- ultrasonic sensors
- laser gun
- light gate
Describe ticker timers.
- create representations of motion in a straight line.
- a strip of paper is passed through the machine, marking the paper at regular intervals.
- 50 dots per second, 0.2 seconds per dot
- speed = distance between 5 dots / 0.1 (d/t)
List the advantages and disadvantages of ticker timers.
Advantages:
- cheap
- low technical knowledge required.
Disadvantages:
- mechanical errors (paper jam)
- doesn’t register stationary or backward motion..
Describe the features of a speed time graph.
Demonstrates changes in speed over time.
Gradient = (final speed - initial speed) / time.
Acceleration = gradient.
Describe the features of a distance time graph.
Demonstrates changes in distance of a moving object.
Gradient = distance / time.
Gradient = average speed.
Define acceleration and provide the formula.
How quickly the velocity of an object changes.
Acceleration = (final velocity - initial velocity) / time.
Given in m/s/s.
Define velocity.
The speed of an object in a given direction.
Compare vector and scalar quantities.
Vector quantities measure magnitude and direction. E.g velocity, displacement.
Scalar quantities measure magnitude only. E.g speed, distance.
Define force.
A push, pull, or twist on an object resulting when two objects interact. Measured in Newtons (N).
Describe Net Force
Net force takes into account all forces acting upon an object and their directions.
Net Force = sum of all forces.
Describe Vectors.
Arrows illustrating the size and direction of forces. Must be to scale.
Describe balanced forces
Objects in balance (Net Force = 0) will not change motion. Will either:
- maintain a constant speed.
- remain stationary.
Describe unbalanced forces.
Unbalanced object (Net Force ≠ 0) will change their state of motion:
- accelerate or decelerate.
- change direction.
- start/stop moving.
Describe Newtons First Law.
An object in motion will stay in motion unless acted on by an unbalanced force.
Provide examples of Newtons First Law.
- a car stops suddenly and items are ‘thrown forward’ as they continue in their state of motion.
- a car turns left and passengers lean right as they continue in a straight motion.
- an accelerating car requires the unbalanced force of the engine to begin moving.
