A car is moving along a straight (OP). It moves from `O "to" P` in `18 seconds` and returns from `P "to" Q` in 6 seconds, where `OP=360 m` and `OQ=240 m` What are the car the average velocity and average speed of the car in going (a) from `O "to" P` and back to `Q`?

Explanation

(a) For a motion from `O to P`,
Displacement `=360 m`
and path length `=360 m`
Average velocity`= (displacement) /(time) =(360 m)/(18s)`
`=20 ms^(-1)` along `vec (OP)`
Average speed `=(path length)/(time)`
`=(360 m)/(18 s) = 20 ms^(-1)`
(b) For a motion from `O to P` and back to `Q ,
displacement`=OQ =24 0 m`
path length `=OP +PQ =360 + (360 +(360 -240)`
`=360 +120 =480 m`
Average velocity `=(240)/(18+6)`
`= 10 ms^(-1)` along `vec (OP)`
Average speed `=(480)/(18 +6) =20 ms^(-1)`.