Distance and Time (Having a Mental Block.

[PcStudent]

Homework Statement

Car A leaves school when a clock reads 0.0s and travels at 65 km/h. Car B traveling at 90 km/h leaves from a convenience store +10 km away from the school and 15 minutes later than Car A.

a.) What is the displacement of each car after 1.5 hrs.

b.) The two cars pass a gas station at 115 km from the school. When did each car pass the station?

Homework Equations

d=vt

t=d/v

The Attempt at a Solution

I am in a mental block at the moment. I have asked about a problem earlier today on the forums and I been on a roll with the homework ever since. But now I have reached a mental block on the very last problem. I am beginner at physics. Just taught myself the basics today. I've done a few dozen problems that were assigned for homework and had little problem with them.
Would someone be as kind as to descriptively explain to me on how to do this problem. I really want to learn on how to do well in physics, so any tips would be greatly appreciated also. Thanks in advance to all those who took the time to read and/or answer this post.

 

[Delphi51]

Yes, a complicated problem. I would deal with the units first. You probably don't want to change the km/h, so do change that 15 minutes into .25 hour so everything is in km and hours.
For this one you must write a d=vt equation for each car, keeping in mind that the time for the second car starts 15 minutes later, so its "t" will be written "T-.25". Keep "T" to mean the time from when the first car leaves. It isn't clear whether the second car has 10 less or 10 more km to go, so you may want to keep both possibilities in mind. Make "D" stand for the distance from the school in both cases. Once you have your two equations, you can use them to answer the questions.

 

[tomcue]

As a scientist, it's important to remember that mental blocks are a normal part of the learning process. Don't be discouraged, and keep practicing and seeking help when needed. Here are some tips for approaching this problem:

1. Understand the problem: Before jumping into calculations, make sure you understand what the problem is asking. In this case, we have two cars (A and B) traveling at different speeds and starting from different points. We need to find their displacements after a certain amount of time (1.5 hours) and also determine when they pass a gas station.

2. Use the given information: The problem provides us with some important information. Car A is traveling at 65 km/h and Car B is traveling at 90 km/h. Car A starts at 0.0s and Car B starts 15 minutes (or 0.25 hours) later. We also know that the gas station is 115 km from the school.

3. Use the distance formula: The formula d=vt (where d is distance, v is velocity, and t is time) can help us solve this problem. For example, to find the displacement of Car A after 1.5 hours, we can use d=vt and plug in v=65 km/h and t=1.5 hours. This will give us the displacement in kilometers.

4. Consider the starting points: Remember that Car A starts at the school (0.0s) and Car B starts 10 km away from the school. This means that Car B's initial displacement is already 10 km.

5. Determine when the cars pass the gas station: To find when each car passes the gas station, we can use the distance formula again. This time, we know the distance (115 km) and the velocity (65 km/h for Car A and 90 km/h for Car B). We can solve for t to find the time it takes for each car to reach the gas station.

6. Check your answers: Once you have calculated the displacements and times, make sure to check if your answers make sense. For example, if Car A starts earlier and is traveling at a slower speed, its displacement after 1.5 hours should be less than Car B's displacement. Also, make sure the times you calculated for when the cars pass the gas station are reasonable (e.g. not in the future or before the cars even start).

Remember to take your time