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:

v1=4 km/h v2=8 km/h  s=20⋅ 5=20 5 km≐44.7214 km  v=v12+v22=42+82≐4 5 km/h≐8.9443 km/h  t=s/v=44.7214/8.9443=5 hv_{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}

Try another example


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:
#
Dr Math

avatar









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.

Following knowledge from mathematics are needed to solve this word math problem:

Next similar math problems:

  1. The ditch
    prikop 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
    RightTriangleMidpoint_3 Show that the points P1 (5,0), P2 (2,1) & P3 (4,7) are the vertices of a right triangle.
  3. Euclid2
    euclid 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
    vzdalenost 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
    taznice3 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
    vectors_sum0_1 Given vector OA(12,16) and vector OB(4,1). Find vector AB and vector |A|.
  7. Unit vector 2D
    one_1 Determine coordinates of unit vector to vector AB if A[-6; 8], B[-18; 10].
  8. ABS CN
    complex_num Calculate the absolute value of complex number -15-29i.
  9. Theorem prove
    thales_1 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
    img2 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
    collinear Show that the point A(-1,3), B(3,2), C(11,0) are col-linear.
  12. Vector - basic operations
    vectors_1 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
    vectors_2 Given that P = (5, 8) and Q = (6, 9), find the component form and magnitude of vector PQ.
  14. Calculation
    pocty How much is sum of square root of six and the square root of 225?
  15. Coordinates of vector
    vectors_2 Determine the coordinate of a vector u=CD if C(19;-7) and D(-16;-5)
  16. Vector
    vectors Determine coordinates of the vector u=CD if C[19;-7], D[-16,-5].
  17. Square side
    square_analytic_geometry Calculate length of side square ABCD with vertex A[0, 0] if diagonal BD lies on line p: -4x -5 =0.