When the acceleration is 4m / S & sup2; after emergency braking at the speed of 10m / s, then () A. the displacement is 12m within 2S after braking The displacement of B is 12.5m within 2S after braking C. The displacement within 3S after braking is 12m D. the displacement within 3S after braking is 12.5m

When the acceleration is 4m / S & sup2; after emergency braking at the speed of 10m / s, then () A. the displacement is 12m within 2S after braking The displacement of B is 12.5m within 2S after braking C. The displacement within 3S after braking is 12m D. the displacement within 3S after braking is 12.5m

AD
The displacement within the stopping time t = (V end-v beginning) / a = 2.5s.2s can be calculated by using the formula s = V beginning t + (1 / 2) at ^ 2
2.5s has stopped, so the displacement of 3S is actually the displacement of the whole braking process, using the formula "2As = V last square - V first square"