Question

An object travels North at `8 m/s` for `7 s` and then travels South at `3 m/s` for `4 s`. What are the object's average speed and velocity?

Answer 1

speed`=68/11m/s`,Velocity `=4m/s`

Explanation:

Distance traveled due North in 7s @ `8m/s` is =`8xx7=56m`
Distance traveled due South in 4s @ `3m/s` is =`3xx4=12m`
Total Distance traveled `=56m+12m=68m`
Total time taken = `7+4=11s`
So average speed `=(Total Distance )/( time)=68/11m/s`

Now net displacement due North=`56-12=44m` (North,South being oppositely directed)

Hence Average velocity due North`=(Displacement )/(Time)=44/11m/s=4m/s`