Question

Joseph jogs from one end A to the other end B of a straight 300 m road in 2 minutes 30 seconds and then turns around and jogs 100 m back to point C in another 1 minute. What are Joseph’s average speeds and velocities in jogging?

1. from A to B and
2. from A to C?

Answer 1

(a) From A to B.

Time for A to B = 2 min 30s

= 2 × 60 + 30

= 150 s

`"Average speed" = "total distance"/ "time interval"`

= `300/150`

= 2 ms^-1

`"Average velocity" = "displacement"/ "time interval"`

= `300/150`

= 2 ms^-1

(b) From A to C.

Time taken = A to B + B to C

= 150 + 60

= 210 s

Total distance = 300 + 100

= 400 m

∴ `"Average speed" = "total distace"/"time interval"`

= `400/210 `

= 1.9 m s^-1

∴ `"Average velocity" = "displacement"/"time interval"`

= `200/210`

= 0.95 ms^-1