A cable of a suspension bridge is in the form of a parabola whose span is 40 m. The roadway is 5 m below the lowest point of the cable. An extra support is provided across the cable 30 m above the ground level. Find the length of the support if the heights of the pillars are 55 m.

see full answer

Talk to JEE/NEET 2025 Toppers - Learn What Actually Works!

Real Strategies. Real People. Real Success Stories - Just 1 call away

An Intiative by Sri Chaitanya

20 \sqrt{2} ​ m

30 \sqrt{2} ​ m

10 \sqrt{2} ​ m

None

answer is A.

(Unlock A.I Detailed Solution for FREE)

Ready to Test Your Skills?

Check your Performance Today with our Free Mock Test used by Toppers!

Take Free Test

Detailed Solution

Equation of parabola is,

x^{2} = 4 ay

Since, the span of the parabola is 40 m. So, x−co−ordinate of A=20
The height of the pillars are 55 meters=AB
So, the co-ordinates of point A = (20, 50)
Let the support be PQ
So, equation of the parabola gets reduced to

x^{2} = 8 y

Identifying the point

Q (x_{1} ​, 25)

x_{1} ​ = 10 \sqrt{2}

PQ = 2 x_{1} ​

= 20 \sqrt{2} ​m

Option 1 is Correct.

Watch 3-min video & get full concept clarity

Result Producing online coaching for JEE/NEET of south India

Largest All India Test Series for JEE/NEET

Best Books for IIT JEE

Best Books for NEET

How to Join IIT after 10th

Best Courses for You

JEE

NEET

Foundation JEE

Foundation NEET

CBSE

Get Expert Academic Guidance – Connect with a Counselor Today!

Result Producing online coaching for JEE/NEET of south India

Largest All India Test Series for JEE/NEET

Best Books for IIT JEE

Best Books for NEET

How to Join IIT after 10th