An object travels North at 2 m/s for 1 s and then travels South at 4 m/s for 9 s. What are the object's average speed and velocity?

1 Answer
IDKwhatName
Jun 26, 2017

Average velocity = "-"3.09..."ms"^-1 "south"
Average speed = 3.45..."ms"^-1

Explanation:

We will deal with speed first. Speed is how far something travels per second.

North - "speed"*"time"="distance"; 2*1=2"m"
South - "speed"*"time"="distance"; 4*9=36"m"

Total distance travelled = 2+36=38m
Total time = 2 + 9 = 11s

"Average speed" = "total distamce"/"total time"

"Average speed" = 38/11 = 3.45..."ms"^-1

Average velocity:

As average takes direction into accpunt as well, the north value will be taken as positive, and the south value as negative (opposite directions, think add and subtract).

North - "velocity"*"time"="displacement"; 2*1=2"m"
South - "velocity"*"time"="displacement"; "-"4*9="-"36"m"

Total displacement = 2-36=-34m
Total time = 2 + 9 = 11s

"Average velocity" = "total displacement"/"total time"

"Average velocity" = "-"34/11 = -3.09..."ms"^-1

As the value for average velocity is negative, and so is the inital south value, the average velocity is therefore "-"3.09..."ms"^-1 "south".

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