標題:

phy-acceleration

發問:

A car travels along a straight line at 63 kmh ^ -1. When driver notices the traffic light ahead turns red, he breaks the car with uniform deceleration at once. The car travels a distance of 30m b4 it stops just in front of the traffic light. Find the deceleration of the car 點解u = 63/3.6 ms-1?? 更新: 應該系話點解u = 63/3.6 ms-1??而唔係v =63/3.6 ms-1??

最佳解答:

from the question: 63 km h-1 is the initial velocity of the car beforce the driver braked the car. 0 km h-1 is the final velocity of the car beacuse the driver braked the car. In PHY, u stands for initial velocity while v stands for final velocity ( u and v are bold letters as they are vectors) you should note it carefully while applying physic formulae

其他解答:

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此文章來自奇摩知識+如有不便請留言告知

63km/h=63000m/3600s=63/3.6m/s km/h同ms-1是有個constant差(3.6) ---------------------------------------------------- km/h=m/s x 3.6
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