An object travels North at 4 m/s for 1 s and then travels South at 5 m/s for 3 s. What are the object's average speed and velocity?

1 Answer
Y ยท Astralboy
May 14, 2017

Average Speed: 4.75 m/s
Average Velocity: -2.75 m/s

Explanation:

To calculate the object's average speed (direction doesn't matter), we use the formula:
s_(avg)=("total distance")/("change in time")

We know that the object traveled for 4 m/s for 1 s then traveled 5 m/s for 3 s, therefore:
4(1)+5(3)=4+15=19 is the total distance traveled in meters
1+3=4 is the change in time

Therefore,
s_(avg)=19/4=4.75 m/s

To calculate the object's average velocity (direction matters), we use the formula:
v_(avg)=("displacement")/("change in time")

Let North be positive and South be negative. We know that the object traveled +4 m/s for 1 s then traveled -5 m/s for 3 seconds, therefore:
4(1)-5(3)=4-15=-11 is the total displacement in meters
1+3=4 is the change in time

Therefore,
v_(avg)=-11/4=-2.75 m/s

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