Word problem

[severincr]

Two race cars A and B start simultaneously from the start and go at a constant speed on a circuit, the car had a higher speed. After a while, car A "catches up" on B at the point located 130 meters after the starting line. After a while, car A catches up with B at the point 60 meters before the start line. It looks like if the cars go on indefinitely, then there would be a time when car A catches up with B exactly on the starting line.

[HallsofIvy]

Two race cars A and B start simultaneously from the start and go at a constant speed on a circuit, the car had a higher speed. After a while, car A "catches up" on B at the point located 130 meters after the starting line. After a while, car A catches up with B at the point 60 meters before the start line. It looks like if the cars go on indefinitely, then there would be a time when car A catches up with B exactly on the starting line.

I assume you meant to say that A had the higher speed and that "catching up" means that A has gone a full lap further than B.

Start by assigning "names" to the missing data. Let "d" be the distance around the circuit, "u" be A's speed, and "v" be B's speed with u> v. If "t1" is the time A first catches up ("laps") B then ut1= vt1+ d. We are told that is "130 meters after the starting line so vt1= 130 and u1t= 130+ d. If t2 is the second time A laps B then ut2= vt2+ 2d. We are told that is "60 meters before the starting line". Then vt2= d- 60 and ut2= 3d- 60.

That is four equations, vt1= 130, ut1= 130+ d, vt2= d- 60, and ut2= 3d- 60. Unfortunately we have 5 unknown values, u, v, d, t1,and t2. You could, and it might be useful, solve for u, v, t1, and t2 in terms of d.

However, I am not clear what you are asking or even if you are asking a question! You say, "It looks like if the cars go on indefinitely, then there would be a time when car A catches up with B exactly on the starting line". I don't think that necessarily follows. They might meet just before the finish line on some laps and just after the finish line on another lap.

[vacebi]

This is a classic physics problem involving relative motion, and it can be solved using algebra and the concept of relative velocity.

Let's assume that car A is faster than car B, and let the speeds of car A and car B be V_A and V_B, respectively. To find the time it takes for car A to catch up with car B at the starting line, we need to set up some equations based on the information provided.

First, when car A catches up with car B at a point 130 meters after the starting line, we can set up an equation for the distance traveled by each car:
For car A: Distance = V_A * t, where t is the time it takes for car A to catch up with car B.
For car B: Distance = V_B * t + 130 meters, because car B has a head start of 130 meters.

After a while, car A catches up with car B at a point 60 meters before the starting line. We can set up a similar equation:
For car A: Distance = V_A * t, but this time, it's catching up 60 meters before the starting line.
For car B: Distance = V_B * t - 60 meters, because car B is 60 meters ahead of the starting line when car A catches up.

Since both of these situations describe the same event (car A catching up with car B), we can set these two equations equal to each other:
V_A * t = V_B * t + 130
V_A * t = V_B * t - 60

Now, we need to find the time, t, when these equations are true. We can simplify the equations:
V_A * t - V_B * t = 130
V_A * t - V_B * t = -60

Now, solve for t:
130 = V_A * t - V_B * t
t * (V_A - V_B) = 130

t = 130 / (V_A - V_B)

Now, we have the time it takes for car A to catch up with car B at the starting line. If we let time continue indefinitely, there will be a time when t = 0, and at that moment, car A will catch up with car B exactly on the starting line. This shows that the cars will meet at the starting line eventually.

So, the answer is that, given the information provided, car A will catch up with car B exactly on the starting line at some point in the future.

[Poeth1952]

Two race cars A and B start simultaneously from the start and go at a constant speed on a circuit, the car had a higher speed. After a while, car A "catches up" on B at the point located 130 meters after the starting line. After a while, car A catches up with B at the point 60 meters before the start line. It looks like if the cars go on indefinitely, then there would be a time when car A catches up with B exactly on the starting line.

Yes — eventually A will overtake B exactly at the start line.
vA​Δt=(integer)⋅L+(L−60)−130=(integer)⋅L+(L−190).