A professional race-car driver buys a car that can accelerate at +5.9m/s^2.The racer decides to race against another dri
A professional race-car driver buys a car that can accelerate at +5.9m/s^2.The racer decides to race against another driver in a souped up stock-car.Both start from rest,but the stock-car driver leaves 1.0s before the driver of the race car.The stock car moves with a constant acceleration of +3.6m/s^2.
a.find the time it takes the race-car driver to overtake the stock-car driver.
b.Find the distance the two drivers travel before they are side by side.
c.find the velocities of both cars at the instant they are side by side.
一个专业的赛车手,买了车,可以在+5.9米/秒^2加速.赛车手决定和另一个司机经改装的一辆车进行比赛.都开始休息,然后改变车司机离开提前1.0秒的赛车司机.改装车的加速度+3.6米/秒^2.
A.找到赛车手超过改装车所花费的时间.B.找到两位车手并排在一起时,距离出行地的距离.C.找到两辆车在即时他们并排的速度.他们是并排的瞬间.
A.设超车所用时间为t,超车时刻二车到达同一位置.
赛车手：x1=a1t^2/2=5.9t^2/2
改装车：x2=a2(t+1)^2/2=3.6*(t+1)/2
到达同一位置：x1=x2
5.9t^2/2=3.6*(t+1)/2
t=3.5s
B.x1=5.9*3.5^2/2=36.1m
C.赛车手车速v1=a1t=5.9*3.5=20.65m/s
改装车车速v2=a2t=3.6*(3.5+1)=16.2m/sA的答案是4.6s 不是3.5s. 我不知道怎么做的。而且比他提前1秒不是应该用更少的时间吗？为什么不是t－1？A改变车司机离开提前1.0秒。所以到相遇的时间应该是3.5+1=4.5s.小数点后面有误差。 赛车手用的时间是t=3.5s,改装车用的时间就是t+1. 当然，如果我们设改装车用时间为t，赛车手用的时间为是t-1了。