Solve Kinematic Problem: Car from A to B at 120km/h & Car from C to B at 80km/h

[Hisanagi]

I am so confused right now. This is porbably a really easy question to answer but I'm just too stupid to understand it...

So onto my question..a car drives 120km/h from point A to B (which is 150km).

When does a second car need to leave from point C (which is in between point A and B and is 76km before B), at 80km/h in order to get to point B at the exact same time as the first car?


xD

 

[gunblaze]

Oh my.. Dun have so little confident in urself man.. Perhaps, to easier ur understanding, You may want to draw out ur velocity-time for the two cars. You can then form 2 eqns. I won't write out the full solns.<<<read the guidelines, if u wan to know why?>>>

You know that the area under the velocity-time graph is the distance travelled. By using the eqn of motion. Try figuring out the soln urself. If cha still got prob, can post out ur prob then we can further analyse it. Just at least show some working. hehe. Happy solvin./

 

[kyle8921]

Don't worry, this can be a bit confusing at first! Let's break it down step by step:

1. We know that the first car is traveling at a speed of 120km/h from point A to B, a distance of 150km. We can use the formula speed = distance/time to find the time it takes for the first car to reach point B.

2. So, time = distance/speed = 150km/120km/h = 1.25 hours.

3. Now, we need to figure out when the second car needs to leave from point C in order to reach point B at the same time. Since the second car is traveling at a speed of 80km/h, we can use the same formula to find the time it takes for the second car to travel from point C to B.

4. We know that the distance from C to B is 76km, so time = distance/speed = 76km/80km/h = 0.95 hours.

5. However, this is just the time it takes for the second car to reach point B from point C. We need to add this time to the time it takes for the first car to reach point B from A.

6. So, the total time for the second car to reach point B at the same time as the first car is 1.25 hours + 0.95 hours = 2.2 hours.

7. Therefore, the second car needs to leave from point C 2.2 hours before the first car reaches point B. We can use this time to calculate the exact time the second car needs to leave from point C, based on the time the first car leaves from point A.

I hope this helps! Just remember to use the formula speed = distance/time and break down the problem step by step. Good luck!