Question

An object travels North at `4 m/s` for `9 s` and then travels South at `6 m/s` for `2 s`. What are the object's average speed and velocity?

Answer 1

Average Speed `=48/11=4.bar36`m/sec
Average Velocity `=24/11=2.bar18" "`m/sec directed North

Explanation:

The given data

Directed North `v_1=4" "`m/sec for time `t_1=9" "`sec
Directed South `v_2=6" "`m/sec for time `t_2=2" "`sec

distance `d_1=v_1*t_1=4*9=36" "`m
distance `d_2=v_2*t_2=6*2=12" "`m

Average speed `=(d_1+d_2)/(t_1+t_2)=(36+12)/(9+2)=48/11=4.bar36" "`m/sec

Average Velocity `=(+36+(-12))/(9+2)=24/11=2.bar18" "`m/sec

God bless....I hope the explanation is useful.