Calculating Avg Velocity of Car in Rural Rally

In summary, the motion depicted in Figure 1 shows the path of a car rally team in a rural area with a speed limit of 80 km/h. Points are deducted for breaking the speed limit. The average velocity of the car's motion for the entire trip is 23.1 km/h [E], calculated by dividing the total displacement (31 km) by the total time (1.3375 hours). This is slightly different from the textbook's answer of 25 km/h [E], which is likely due to the assumption of constant maximum speed.
  • #1

Homework Statement



The motion depicted in Figure 1 shows the path of a team in a car rally held in a rural area where the speed limit is 80 km/h. In the car rally, points are deducted for anyone determined to be breaking the speed limit.

c) Determine the average velocity (magnitude and direction) of the car's motion for the entire trip.

The race track kind of looks like the one I attached.


side A = 23 km = side C
side B = 46 km
that small part, D = 15 km
x = start
v, >, <, ^ show the direction.

Homework Equations



Vavg = (delta x)/(delta t)

The Attempt at a Solution



(I already did the first parts)
The total displacement (delta x) is from x to D. So that would be 46-15 = 31 km.
Total time is ?? Assuming that they don't surpass the speed limit, they are going 80km/h. Knowing that, and that they go a total of 107 km... (46+23+23+15) ... they will take 1. 3375h. So...then wouldn't it be 31/1.3375 = 23.1 km/h [E] (East because displacement is only eastward)

The answer the book gave was 25 km/h [E].
What'd I do wrong??
 

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  • #2
Your answer looks OK to me. (Even though you assume that the car always travels at its maximum speed. :wink:)
 
  • #3
Silly textbook...

Thanks!
 

1. How is average velocity calculated in a rural rally?

The average velocity in a rural rally is calculated by taking the total distance traveled and dividing it by the total time taken to complete the rally. This will give you the average speed in units of distance per time, such as miles per hour or kilometers per hour.

2. What factors can affect the average velocity of a car in a rural rally?

There are several factors that can affect the average velocity of a car in a rural rally, including the terrain, weather conditions, road conditions, and the skill of the driver. Uphill or downhill sections, sharp turns, and slippery roads can all impact the average velocity of a car.

3. How does the type of car affect the average velocity in a rural rally?

The type of car can greatly impact the average velocity in a rural rally. Cars with more powerful engines and better handling will have a higher average velocity compared to cars with less power and poorer handling. Additionally, the weight and aerodynamics of the car can also affect its average velocity.

4. Is average velocity the same as average speed?

While average velocity and average speed are often used interchangeably, they are not exactly the same. Average velocity takes into account the direction of motion, while average speed only considers the magnitude of the motion. In a rural rally, the average velocity would be the average of the car's speed and direction over the entire rally.

5. Can average velocity be calculated for different sections of a rural rally?

Yes, average velocity can be calculated for different sections of a rural rally. This can be useful in analyzing the performance of a car and driver in different terrains or road conditions. To calculate the average velocity for a specific section, divide the distance traveled in that section by the time it took to complete it.

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