<span>Dawn was at 6 am.
Variables
a = distance from a to passing point
b = distance from b to passing point
c = speed of hiker 1
d = speed of hiker 2
x = number of hours prior to noon when dawn is
The first hiker travels for x hours to cover distance a, and the 2nd hiker then takes 9 hours to cover that same distance. This can be expressed as
a = cx = 9d
cx = 9d
x = 9d/c
The second hiker travels for x hours to cover distance b, and the 1st hiker then takes 4 hours to cover than same distance. Expressed as
b = dx = 4c
dx = 4c
x = 4c/d
We now have two expressions for x, set them equal to each other.
9d/c = 4c/d
Multiply both sides by d
9d^2/c = 4c
Divide both sides by c
9d^2/c^2 = 4
Interesting... Both sides are exact squares. Take the square root of both sides
3d/c = 2
d/c = 2/3
We now know the ratio of the speeds of the two hikers. Let's see what X is now.
x = 9d/c = 9*2/3 = 18/3 = 6
x = 4c/d = 4*3/2 = 12/2 = 6
Both expressions for x, claim x to be 6 hours. And 6 hours prior to noon is 6am.
We don't know the actual speeds of the two hikers, nor how far they actually walked. But we do know their relative speeds. And that's enough to figure out when dawn was.</span>
Answer:49 sec
Step-by-step explanation:
Given
Maximum speed to reach is 183.58 mi/h
Length of course is 5 mi
acceleration rate is defined by 60mi/h in 4 sec
therefore acceleration(a)![=\frac{v-u}{t}](https://tex.z-dn.net/?f=%3D%5Cfrac%7Bv-u%7D%7Bt%7D)
![a=\frac{60\times 60\times 60}{4}](https://tex.z-dn.net/?f=a%3D%5Cfrac%7B60%5Ctimes%2060%5Ctimes%2060%7D%7B4%7D)
![a=54\times 10^3 mi/h^2](https://tex.z-dn.net/?f=a%3D54%5Ctimes%2010%5E3%20mi%2Fh%5E2)
To reach a speed of 183.58mi/h with an acceleration of ![54\times 10^3 mi/h^2](https://tex.z-dn.net/?f=54%5Ctimes%2010%5E3%20mi%2Fh%5E2)
Using equation of motion
v=u+at
![183.58=0+(54\times 10^3)t](https://tex.z-dn.net/?f=183.58%3D0%2B%2854%5Ctimes%2010%5E3%29t)
![t=\frac{183.58}{54\times 10^3}](https://tex.z-dn.net/?f=t%3D%5Cfrac%7B183.58%7D%7B54%5Ctimes%2010%5E3%7D)
t=0.00339 hours
t=12.23 s reach maximum speed
To complete course it takes
![s=ut+\frac{1}{2}at^2](https://tex.z-dn.net/?f=s%3Dut%2B%5Cfrac%7B1%7D%7B2%7Dat%5E2)
![5=0+\frac{1}{2}\times 54\times 10^3 \times t^2](https://tex.z-dn.net/?f=5%3D0%2B%5Cfrac%7B1%7D%7B2%7D%5Ctimes%2054%5Ctimes%2010%5E3%20%5Ctimes%20t%5E2)
t=0.01360 hour
or ![t=48.98\approx 49 s](https://tex.z-dn.net/?f=t%3D48.98%5Capprox%2049%20s)
Answer:
C
Step-by-step explanation:
PLEASE MARK BRAINLIEST
Answer:
11.20
Step-by-step explanation:
Multiply both equations by 100:
19.99=1999
8.79=879
1999-879=1120
Divide by 100:
1120/100=11.20 saved ................
Answer:
1728 for A
7290000 for B
Step-by-step explanation: