Vavg = (V1 + V2) / 2,
V1 = velocity for 1st half of trip,
V2 = velocity for 2nd half of trip,
2.5 m/s = (1 m/s + V2) / 2,
Cross multiply:
1 + V2 = 5,
V2 = 5 - 1 = 4 m/s = 9 mi/hr.
She will have to average 4 m/s or
9 mi/hr for the 2nd half of trip.
Quite a task!
Solve for V2:
Annie is walking to school leisurely at a speed of 1.0 m/s for the first half of her trip. She then remembers that her physics teacher told her that she must average 2.5 m/s to make it to school on time. Realizing she might be late, she starts running. However, after a quick calculation, she stops running--she's going to be late anyways.
a) show why she can't make it on time
1 answer