New Delhi Metro

On the New Delhi metro, the Shivaji Bridge station is about 400 m north and 150 m east of the Barakhambha Road station. If I walk directly from one station to the other at a speed of 2 m/s, how long does it take me to walk between the stations in seconds ?

Image source: The Hindu


The answer is 213.6.

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30 solutions

Adi Pratama
Dec 27, 2013

s = √ ( 400m² + 150²)

s = 427.2 m

t = s / v

t = 427.2m / 2m/s

t = 213.6 s

the pythagorean theorem

Yunus Arefin - 7 years, 5 months ago

pythagoras

OK

Nivedita Singh - 7 years, 4 months ago

can you please justify the first step you have done

Animesh Mishra - 7 years, 5 months ago

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We need to find the distance between the two stations so we will use Pythagorus' theorem. Let point A A be the Barakhambha Road station, let 400 m 400m north of this be B B and let C C be the Shivaji Bridge station. Then A B C ABC is a right triangle. We need to find the distance A C = A B 2 + B C 2 = 40 0 2 + 15 0 2 = 427.2 m AC = \sqrt{AB^2 + BC^2} = \sqrt{400^2 + 150^2} = 427.2m

Oliver Welsh - 7 years, 5 months ago

same question from me also !

Devesh Rai - 7 years, 5 months ago

Its all about vector, bud.

andre yudhistika - 7 years, 5 months ago

how i can use symbols and subscripts/superscripts in writing solution

mukesh kumar - 7 years, 5 months ago

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You can read formatting guide here

Muh. Amin Widyatama - 7 years, 5 months ago

got it

Ravalee Kanthi Ravuri - 7 years, 4 months ago

thankyou

ram kumar - 7 years, 4 months ago

pythagrs thrm

Gallardo Ahmad - 7 years, 4 months ago
Prasun Biswas
Dec 28, 2013

If we represent this data in a graph, we see that the walking distance from one station to another is the hypotenuse of the triangle so formed with the other 2 sides being 150 m and 400 m. Given speed of person = 2 =2 m/s

So, required distance = 15 0 2 + 40 0 2 = 22500 + 160000 = 182500 = 427.20 m =\sqrt{150^{2}+400^{2}} = \sqrt{22500+160000} = \sqrt{182500} = \boxed{427.20} m

Now, Time = D i s t a n c e S p e e d = 427.20 2 = 213.60 s e c =\frac{Distance}{Speed} = \frac{427.20}{2} = \boxed{213.60} sec

Akshat Jain
Oct 1, 2013

Since the polar directions East and North are perpendicular to eachother, the figure formed will be a right angled triangle, with height 400 m 400m and base 150 m 150m . Therefore, the distance covered on walking directly from one station to the other is represented by the hypotenuse, that comes out from the Pythagoras Theorem-

40 0 2 + 15 0 2 = H 2 400^2 + 150^2 = H^2

H 2 = 18250 H^2 = 18250

H = 427.20 H = 427.20

Therefore, the distance is 427.2 m 427.2m .

Now, we have to calculate the time. We know that t = s v t = \frac{s}{v} , where t = t = time, s = s = distance and v = v = velocity.

Putting the values, we get-

t = 427.20 2 = 213.60 t = \frac{427.20}{2} = \fbox{213.60}

So similar to mine .

Priyansh Sangule - 7 years, 8 months ago
Priyansh Sangule
Sep 30, 2013

According to the problem, we get a right triangle with sides 400 400 m and 150 150 m each .

We have to find the displacement between the two stations , i.e the hypotenuse of the triangle .

Hence , we find the * hypotenuse * i.e the distance (d) :

d 2 = ( 400 ) 2 + ( 150 ) 2 d^2 = (400)^2 + (150)^2

d 2 = 160000 + 22500 d^2 = 160000 + 22500

d = 182500 d = \sqrt{182500}

d = 427.2 d = 427.2

Now , since :

s p e e d = d i s t a n c e t i m e t i m e = d i s t a n c e s p e e d speed = \dfrac{distance}{time} \Rightarrow time = \dfrac{distance}{speed}

Therefor by putting the values :

t i m e = d i s t a n c e s p e e d = 427.2 2 = 213.6 s \Rightarrow time = \dfrac{distance}{speed} = \dfrac{427.2}{2} = \boxed{213.6} s

silly mistake

Tarun Gupta - 7 years, 8 months ago

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Can you please be more specific about the mistake ?

Priyansh Sangule - 7 years, 8 months ago
Oliver Welsh
Sep 29, 2013

Using Pythagorus' Theorem, we can see that the distance directly between the two places is:

40 0 2 + 15 0 2 = 427.1 \sqrt{400^2 + 150^2} = 427.1\dots

We know that t i m e = d i s t a n c e s p e e d time = \frac{distance}{speed} , so using this value, we find that the time in seconds is:

427.1 2 = 213.6s \frac{427.1\dots}{2} = \fbox{213.6s}

Sam Leo
Jan 2, 2014

We first need to calculate the distance,s, between the 2 stations, for which we use pythagoras theorem. s = 40 0 2 + 15 0 2 = 427.200 s = \sqrt{400^{2}+150^{2}} = 427.200 We know the speed and the distance, so we simply need to calculate the time using distance/speed.

Therefore, time taken = s 2 = 213.6 s \frac{s}{2} = 213.6s

my solving process is similar to Sam Leo. Thanks Sam Leo to solve before me.

Rubel Haque - 7 years, 5 months ago
Nishanur Rahman
Mar 9, 2014

We need to find the distance between the two stations so we will use Pythagorus' theorem. Let point A be the Barakhambha Road station, let 400m north of this beB and let C be the Shivaji Bridge station. Then ABC is a right triangle. We need to find the distance AC=s. s = √ ( 400m² + 150²)

s = 427.2 m

t = s / v

t = 427.2m / 2m/s

t = 213.6 s

Vikash Samrat
Mar 7, 2014

Displacement s=427.2001873 m velocity v=2 m/s Time t= displacement/velocity t=427.2001873/2=21306000936

Aravind Raj
Mar 2, 2014

s = √ ( 400m² + 150²)

s = 427.2 m

t = s / v

t = 427.2m / 2m/s

t = 213.6 s

Ephraim Raj
Feb 27, 2014

Pythagoras theorem

Kishan Ahir
Feb 6, 2014

one station being 400 m and other 150 m , we need to take vector sum we get 427 m this distance we need to travel from one station to other n den dividing it by velocity 2 m/s we get Time= 214

Avisek Agarwal
Jan 19, 2014

Its applies pythogoras theorem

Lets say the distance be x

x^2=400^2 + 150^2

x^2=182500

x=427.2

So distance- 427.2 m and speed = 2 m/s

T=d/s

Time=427.2/2=213.6 seconds.

Avinash Prabhakar
Jan 10, 2014

Use Pythagoras Theorem to find the exact distance b/w the two points and then calculate the time using Time=Distance/Velocity=213.6 approx. 214

the distance between the shivaji bridge and the Barahkhamba road can be found out by the Pythogras theorem. therefore a triangle has been formed with the base equal to 400 m and the height equal to 150 m.so distance (hypotenuse)= root of(base ^2 +height^2).Here-distance=root(160000+22500) =square root of 182500=427.200(distance) as speed equals distance/ time =>2=427.2/time =>time=427.200/2 =213.600

Pushkar Pandit
Jan 5, 2014

If I walk between the two stations then i have to walk through a direct path between 2 stations not the metro path......ie D=[(400)^2+(150)^2]^(1/2)=427.2 m So, t=D/v=427.2/2= 213.6 secs

The distance between the 2 stations is 150+400 = 650 m. However, walking directly between the 2 stations represents displacement. Using pythagoras theorem, we find that displacement^2 = 150^2 + 400^2-----> d = sqrt.182500 = 427.200187266. Now, time = distance/speed-------------> 427.200187266/2 = 213.600093633=Answer

Mukesh Kumar
Dec 28, 2013

actual distance between the two stations= sqrt(400 400+150 150)=427.200 walking speed=2m/s hence time taken in seconds=distance/speed =427.200/2 =213.600

Pythagoras is Elementary School.

Jasper Lee
Feb 15, 2014

A^2 + B^2= C^2, to get a distance of 427.2. Divide by 2 to get 213.6.

Atiq Ur Rehman
Jan 27, 2014

Displacement is measure by Pythorgoras Theorem (as 150 m towards East and then 400 towards North ; makes a right angle triangle). When displacement is measured then we simply use the formula; Velocity = Displacement/Time and calculate time .

Lucky Khan
Jan 26, 2014

simple calculate the length of line by (x1-x2)^2+(y1-y2)^2 as a whole under root, and divide it by speed u will get time that 214

s=sqrt(400^2+150^2) s=427.2 m V=2m/s => t=S/V t= 213.6sec

Mohamed Ramadan
Jan 7, 2014

Suppose that the station is the point of origin the Shivaji Bridge is 400 meters to the north and impose this point of (A) and 150 meters to the east and impose this point (B) and draw a straight line up between (A) and (B) we can calculate the distance between these two dots using the theory of Pythagoras triangle-based We get the distance (X) the distance between these two dots by using the relationship [X = V * T] Where (V) Speed we get (T) the time required

Abubakarr Yillah
Jan 2, 2014

Let the resultant distance between the two stations be D

By Pythagoras theorem

(400)^2 + (150)^2=D^2.

Hence D ₌ 50√73 m

From speed ₌ Distance/Time

       Time ₌ Dinstance/Speed

Thus Time ₌ (50√73)/2

Therefore the time in seconds ₌ 213.6 s

The distance between New Delhi station to Shivaji Bridge station is equal 40 0 2 + 15 0 2 = 50 73 \sqrt {400^2+150^2}=50\sqrt {73}

Thus the time needed to reach one station from another station if we walk with 2 m / s 2 m/s speed is

50 73 2 = 213.600 \frac {50\sqrt {73}}{2}=213.600

Star Buck
Dec 28, 2013

4oo^2+150^2=427.200^2

427.200/2=213.600

Daniel Ferreira
Oct 5, 2013

( Δ S ) 2 = ( 400 ) 2 + ( 150 ) 2 ( Δ S ) 2 = 182500 Δ S = 427.2 m \\ \left ( \Delta S \right )^2 = \left ( 400 \right )^2 + \left ( 150 \right )^2 \\\\ \left ( \Delta S \right )^2 = 182500 \\\\ \Delta S = 427.2 \; \text{m}

Por fim,

S = v t 427.2 = 2 t t = 213.6 s \text{S = v} \cdot \text{t} \\\\ 427.2 = 2\text{t} \\\\ \boxed{\text{t = 213.6 s}}

Srikanth Tumati
Oct 1, 2013

This is basically the Pythagorean Theory which is a squared plus b squared equals c squared. I did 400 squared plus 150 squared which gave me a number. Then i found the square root of that number and divided that by 2 to get the seconds.

Manjit Yadav
Sep 30, 2013

since these two directions are perpendicular to each other hence the distance to be covered if we go directly is \sqrt{400^2+150^2} m. this is obtained using Pythagoras theorem. hence the time taken is distance covered\speed

Fintan Pan
Sep 29, 2013

(Square root (400^2+150^2) )divide by 2

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