8.3 Linear Motion Flashcards
What is average speed?
Average speed looks at the entire journey. Total distance and total time.
Average speed does not provide much information about the speed at any instant during the journey.
What is instantaneous speed?
The instantaneous speed is the speed of the car at any given point along the journey.
How is instantaneous or average speed determined?
Sonic Motion Sensors
Speedometers
Radar Guns – send out radio waves
Laser guns – send out pulses of light
Digitectors – two cables laid across the road at a fixed distance
Global Positioning System (GPS)
Personal Sports Trackers
How do Sonic motion detectors measure speed?
Sonic motion detectors measures the time it takes for a high frequency sound pulse to travel from the detector to an object and back.
Using this round-trip time and the speed of sound, it can determine the distance to the object - its position.
Using the change in position it is possible to calculate the object’s velocity and acceleration
Sonic motion detectors are used in car bumper bars and give warning beeps when close to another object.
How do ticker times measure speed?
A ticker timer can be used to record motion in the science lab.
A vibrating arm hits a disk of carbon paper 50 times each second, leaving black dots that are a fiftieth of a second apart.
How can you use ticker times to measure speed?
We can measure the average speed between each pair of dots by dividing the distance by the time interval.
