# Distance travelled

1. Aug 3, 2010

### thereddevils

1. The problem statement, all variables and given/known data

Find the distance travelled by the car from point A to D. From A to B, the car travels at an average speed of 30 km/h, from B to C, 60 km/h and from C to D 40 km/h. The whole journey took 6 hours.

2. Relevant equations

3. The attempt at a solution

In 2 hours, the car travels a distance of 60km, 120km, and 80 km respectively so the total distance travelled would be 260 km.

2. Aug 3, 2010

### rl.bhat

In 2 hours, the car travels a distance of 60km, 120km, and 80 km respectively so the total distance travelled would be 260 km.

It is not correct. The time interval between A to B, B to C and C to D is not equal.

Find the average velocity from A to D. The distance traveled = The average velocity x time.

3. Aug 3, 2010

### Isiudor

Either there's something I'm missing or the above problem cannot be solved using only what you wrote.

there's no way to calculate the average velocity since it's unknown how long was spent in each section or the distance traveled in each section...

Are you sure there wasn't additional data?

4. Aug 3, 2010

### thereddevils

Do i sum up all the velocities and divide them by 3

ie (80+60+120)/3 ?

5. Aug 3, 2010

### Staff: Mentor

Are you posting the problem exactly as it was given? As Isiudor points out, there does not seem to be sufficient information to solve it.

For example:
A to B for one hour (30 km), B to C for one hour (60 km), C to D for four hours (160 km); total distance = 250 km.

On the other hand:
A to B for two hours (60 km), B to C for one hour (60 km), C to D for three hours (120 km); total distance = 240 km.

There are an infinite number of solutions.

6. Aug 4, 2010

### thereddevils

yeah that's the question given, except for the description of the journey. The original question says go up the slope, then going down ... i just used A,B,C,D to replace them for convnience.

Maybe i am expected to give any one of the infinite solutions.

7. Aug 4, 2010

### arkofnoah

i'd say post the original question. You might be missing out some crucial implicit information (perhaps like acceleration due to gravity and stuff).

8. Aug 4, 2010

### thereddevils

ok i will repost the complete question when i get my question paper back.