# Two people

Two straight lines cross at right angles. Two people start simultaneously at the point of intersection. John walking at the rate of 4 kph in one road, Jenelyn walking at the rate of 8 kph on the other road. How long will it take for them to be 20√5 km apart

Result

t =  5 h

#### Solution:

$v_{1}=4 \ \text{km/h} \ \\ v_{2}=8 \ \text{km/h} \ \\ \ \\ s=20 \cdot \ \sqrt{ 5 }=20 \ \sqrt{ 5 } \ \text{km} \doteq 44.7214 \ \text{km} \ \\ \ \\ v=\sqrt{ v_{1}^2+v_{2}^2 }=\sqrt{ 4^2+8^2 } \doteq 4 \ \sqrt{ 5 } \ \text{km/h} \doteq 8.9443 \ \text{km/h} \ \\ \ \\ t=s/v=44.7214/8.9443=5 \ \text{h}$

Our examples were largely sent or created by pupils and students themselves. Therefore, we would be pleased if you could send us any errors you found, spelling mistakes, or rephasing the example. Thank you!

Leave us a comment of this math problem and its solution (i.e. if it is still somewhat unclear...):

Showing 1 comment:

Tips to related online calculators
For Basic calculations in analytic geometry is helpful line slope calculator. From coordinates of two points in the plane it calculate slope, normal and parametric line equation(s), slope, directional angle, direction vector, the length of segment, intersections the coordinate axes etc.
Two vectors given by its magnitudes and by included angle can be added by our vector sum calculator.
Do you want to convert velocity (speed) units?
Pythagorean theorem is the base for the right triangle calculator.

## Next similar math problems:

1. The ditch
Ditch with cross section of an isosceles trapezoid with bases 2m 6m are deep 1.5m. How long is the slope of the ditch?
2. Vertices of RT
Show that the points P1 (5,0), P2 (2,1) & P3 (4,7) are the vertices of a right triangle.
3. Euclid2
In right triangle ABC with right angle at C is given side a=27 and height v=12. Calculate the perimeter of the triangle.
4. Parametric form
Calculate the distance of point A [2,1] from the line p: X = -1 + 3 t Y = 5-4 t Line p has a parametric form of the line equation. ..
5. Medians and sides
Triangle ABC in the plane Oxy; are the coordinates of the points: A = 2.7 B = -4.3 C-6-1 Try calculate lengths of all medians and all sides.
6. Vector 7
Given vector OA(12,16) and vector OB(4,1). Find vector AB and vector |A|.
7. Unit vector 2D
Determine coordinates of unit vector to vector AB if A[-6; 8], B[-18; 10].
8. ABS CN
Calculate the absolute value of complex number -15-29i.
9. Theorem prove
We want to prove the sentence: If the natural number n is divisible by six, then n is divisible by three. From what assumption we started?
10. Line
Line p passing through A[-10, 6] and has direction vector v=(3, 2). Is point B[7, 30] on the line p?
11. Points collinear
Show that the point A(-1,3), B(3,2), C(11,0) are col-linear.
12. Vector - basic operations
There are given points A [-9; -2] B [2; 16] C [16; -2] and D [12; 18] a. Determine the coordinates of the vectors u=AB v=CD s=DB b. Calculate the sum of the vectors u + v c. Calculate difference of vectors u-v d. Determine the coordinates of the vector w.
13. Add vector
Given that P = (5, 8) and Q = (6, 9), find the component form and magnitude of vector PQ.
14. Calculation
How much is sum of square root of six and the square root of 225?
15. Coordinates of vector
Determine the coordinate of a vector u=CD if C(19;-7) and D(-16;-5)
16. Vector
Determine coordinates of the vector u=CD if C[19;-7], D[-16,-5].
17. Square side
Calculate length of side square ABCD with vertex A[0, 0] if diagonal BD lies on line p: -4x -5 =0.