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

Explanation

(a) Average velocity `= ("Displacement")/("Time taken")`
`bar v = (360- 0)/(18) = (360)/(18)`
`therefore bar v = 20 ms ^(-1)`
Average speed `= ("Path length")/("Time taken")`
`= (360)/(18) = 20 ms ^(-1)`
`therefore` The value of Average speed is same as Average velocity
(b) Average velocity `= ("Displacement OQ")/(18 +6)`
` = (240)/(24) `
`bar v = 10 ms ^(-1)` br> Average speed `= ("Path length")/("Time taken")`
`= (OP+ PQ)/(18+6)= (360+ 120)/(24) = (480)/(24) = 20 ms ^(-1)`
Here, Average speed `gt ` Average velocity,