What Is the Average Speed of a Rabbit in a 4 km Race?

No problem, glad to help!In summary, the conversation discussed calculating the average speed of a rabbit in a 4.00km race, where the rabbit took a 90.0min nap after running 0.500km and then ran twice as fast for the remaining distance, completing the race in a total time of 1.75h. It was determined that the average speed of the rabbit was 2.29km/h for the entire race. When calculating the average speed before the rabbit's nap, the correct method was to add the fractions (0.5km / v1) + (3.5km / 2*v1) = (4.5km / 2*v1), resulting in
  • #1
rash219
23
0
Rabbits! Average Speed??

Homework Statement



A rabbit takes part in a 4.00km race. First the rabbit runs 0.500 km then stops and takes a 90.0min nap. when he wakes up he runs twice as fast completing the race in a total time of 1.75h.

A:-Calculate the average speed of the rabbit?
B:-Calculate the average speed of the rabbit before he stopped for a nap??

Homework Equations



Average Speed = Total Distance Traveled / Total Time Taken

The Attempt at a Solution



I got the 1st one, A, the answer to that was 2.29km/h...

Ok i have been trying to sole the 2nd part of this myth but i still can't figure out how to get the 9.00 km/hr.. my attempt is below

Converting 90 min to hrs = 1.5h...therefore actual time taken for the 2 distances would = to 0.25h ie 1.75h - 1.5h

Thus forming the 1st equation T1 + T2 = 0.25h --------(1)

v = avg. speed; d = distance; t = time

now we know that v1 = d1 / t1 and v2 = d2 / t2...
where d1 = 0.5km and d2 = 3.5km
and according to the question we can form another equation stating that

2*v1 = v2 -----------------(2)

using the given formula we can write an equation like

(d1 / v1) + (d2 / v2) = t1 + t2

(0.5km / v1) + (3.5km / 2*v1) = 0.25h

(4.0km / 3*v1) = 0.25h

3*0.25h*v1 = 4.0km

therefore v1 = 4.0km / 0.75h = 5.34 km/hr...

WHAT AM DOING WRONG?

according to my book the answer is 9.00km/h :confused:

Please Help...
 
Last edited:
Physics news on Phys.org
  • #2
Check your working in solving the equation. You have made an error in adding the fractions.

Note that:
[tex]
\frac{a}{b} + \frac{x}{y} \ne \frac{{a + x}}{{b + y}}
[/tex]
 
  • #3
But according to the question the rabbit runs twice as fast so isn't it correct to say that 2 times V1 would equal to V2 ! therefore substituting it in the problem..where v2 = 2 * v1...
 
  • #4
yes that part is right, so this is correct:

(0.5km / v1) + (3.5km / 2*v1) = 0.25h

But remeber, when you add fractions, you need to find a common denominator.
 
  • #5
ok then what is wrong with my final answer...why is the book saying its 9.00km/hr
 
  • #6
You didnt add the fractions correctly.

(0.5km / v1) + (3.5km / 2*v1) [tex]\ne[/tex] (4.0km / 3*v1)

But rather:

(0.5km / v1) + (3.5km / 2*v1) [tex]=[/tex] (4.5km / 2*v1)
 
  • #7
Darn what a silly mistake >_<! Thanks a million...came out right!
 

FAQ: What Is the Average Speed of a Rabbit in a 4 km Race?

What is the average speed of rabbits?

The average speed of rabbits can vary depending on the breed and individual characteristics, but on average, rabbits can run between 25-45 miles per hour.

Do rabbits have a faster average speed than other animals?

Rabbits are not considered the fastest animals, but they do have a relatively fast average speed compared to other animals of similar size. Some animals that are faster than rabbits include cheetahs, horses, and greyhounds.

How does a rabbit's speed compare to their body size?

Rabbits have powerful hind legs that allow them to run quickly and efficiently. Their small size and lightweight body contribute to their fast average speed.

What factors can affect a rabbit's average speed?

Some factors that can affect a rabbit's average speed include the breed, age, health, and overall physical condition. Environmental factors such as terrain and temperature can also impact a rabbit's speed.

Can rabbits maintain their average speed for a long period of time?

Rabbits are known for their quick bursts of speed, but they are not built for endurance running. They can maintain their average speed for short distances, but they will need to rest and recover before running at their top speed again.

Back
Top