The discussion revolves around a kinematics problem involving a race where a car must complete a 1 km course while optimizing for the fastest time. The car has specific acceleration and deceleration rates, which complicate the calculations for the total time required to finish the race.
The discussion is ongoing, with participants sharing their thoughts on the problem setup and calculations. Some have expressed confusion regarding the deceleration phase and the implications of the acceleration on total time. There are indications of productive lines of reasoning, but no consensus has been reached.
Participants are navigating the constraints of the problem, including the need to account for both acceleration and deceleration distances, as well as the requirement for the car to come to a complete stop at the finish line. There is also a mention of potential discrepancies in time estimates based on the given acceleration values.
PhanthomJay said:Yes, its all in the kinematic equations and the fact that the car accelerates at 8 m/s/s over a distance d1, then decelerates over a distance d2 at 5 m/s/s, where d1 + d2 =1000 m. Hint: the car accelerates from 0 to some maximum speed, then decelerates from that same max speed to 0 at the finish line.
Not at an acceleration of 8m/s/s. Even if the car were to cross the finish line without applying the brakes before then, the time would be determined from d=1/2(a)(t)^2, solve t = almost 16 seconds...so since the car is braking well before the finish line in order to stop and have no velocity at the finish line, the total time must be greater than 16 seconds.student1ds said:I think I got an answer but to me it doesn't make sense. Is it possible to complete a 1 km race in 9 seconds ?
One equation is d1 +d2 =1000; you'll then need a couple of the kinematic equations for each portion of the trip (d1 and d2, respectively), to solve for the time of each portion.qswdefrg said:I think I'm on the right track... but I always seem to end up with more variables than equations. :/