A car waiting at a red traffic light accelerates away at 2.0 m/s2 when the
light changes to green. Two seconds later, a lorry moving in the same
direction at 18.0 m/s crosses the same line at the lights and overtakes the car
soon after that. Calculate the distance travelled by the car from the lights
before it is overtaken by the lorry.

Question

A car waiting at a red traffic light accelerates away at 2.0 m/s2 when the
light changes to green. Two seconds later, a lorry moving in the same
direction at 18.0 m/s crosses the same line at the lights and overtakes the car
soon after that. Calculate the distance travelled by the car from the lights
before it is overtaken by the lorry.

anonymous · Answer

assuming that the lorry is moving at that constant speed, this is the equation we have to solve: 18*x=.5*2*(x+2)^2 The x represents the amount of time it took the lorry to over take it after it passed the line. the .5*etc. comes from the equation distance = Initial velocity * time +(1/2) * acceleration*time squared. The reason we add the 2 to the second x is because that had been accelerating for 2 seconds longer. I hope that helps :)

anonymous · Answer

the answer i'm getting for x btw is .29179, which means the distance is 18*.29179 which is 5.252

joachim · Answer

Thanks for your help