An object travels North at # 8 m/s# for #6 s# and then travels South at # 7 m/s# for # 4 s#. What are the object's average speed and velocity?
2 Answers
Average speed
Average velocity
Explanation:
Explanation:
The distance North,
#s_n = v_n*t_n = 8 m/s*6 s = 48 m#
The distance Sorth,
#s_s = v_s*t_s = 7 m/s*4 s = 28 m#
Average speed
#"Average speed " = "total distance"/"total time" " "# So, plugging in our data,
#"Average speed " = (48 m + 28 m)/(6 s + 4 s) = (76 m)/(10 s)#
#"Average speed" = 7.6 m/s#
Average velocity
#"Average velocity " = "total displacement"/"total time"#
To determine displacement, we need a rule for what the positive direction is. I declare that North is the positive direction. So, plugging in our data,
#"Average velocity" = (48 m - 28 m)/(6 s + 4 s) = (20 m)/(10 s)#
#"Average velocity" = 2.0 m/s#
I hope this helps,
Steve