speed Flashcards
what is speed
a measure of how far you travel in a set amount of time
how do you calculate speed
speed = distance over time
what are the three common units for spped
metres per second m/s
miles per hour mph or miles/h
kilometres per hour km/h
what is relative speed
the speed an object is moving from the perspectice of another moving object
what happens when two objects are moving in opposite directions
speed is added if they are going towards each other
what is the relative speed when two objects are moving towards each other at 30km/h and 25km/h
30km/h + 25 km/h = 55km/h
what happens when two objects are mvoing in the same direction
the speeds take away from each other if they are moving in the same direction
what is the relative speed for a tractor moving at 20mph and a car moving at 30 mph
relative speed = 30 - 20 = 10 mph
when does the rule that objects moving in the same direction - subtract speeds and objects moving in the opposite direction add speeds change
it changes when the objects are not travelling on the same straight line
what is a distance time graph
a graph that shows the distance travelled by an object over time
what does a steeper slope show on a distance time graph
it shows th object is moving faster
