Question

一个初速度为零的物体在做匀加速直线运动时,第15s末的速度是7.5m/s那么,它在第9秒内的平均速度是?

Answer 1

a = v/t = 7.5/15 = 0.5m/s²

Vt8 = Vo + at8 = 0 + 0.5*8 = 4m/s

Vt9 = Vo + at9 = 0 + 0.5*9 = 4.5m/s

平均速度 V = ( Vt8 + Vt9)/2 = 4.25m/s