Civil Engineering - Hydraulics - Discussion

Discussion Forum : Hydraulics - Section 3 (Q.No. 9)
9.
A jet projected at an angle of 45θ, 40 m from the foot of a vertical column, just reaches the top of the column. The height of the column is
15 m
20 m
30 m
40 m
60 m.
Answer: Option
Explanation:
No answer description is available. Let's discuss.
Discussion:
14 comments Page 1 of 2.

Gege said:   7 years ago
From any point jet has departed 45° and reaches the height of column (H).
The distance between from any point to the tip of the column is 40m.

This can be calculated using " Angle of Elevation"

Tan(45°) = H/40;
H = 40Tan(45°).
H = 40m.
(4)

Pkota said:   4 years ago
Projectile motion.

Range R=u^2sin2θ/g.
Height H=u^2(sinθ)^2/2g,
Here 40m is R/2 so R=80,
i.e.R=u^2sin2(45°)/g ; 80=u^2/g.

H = u^2 (sin45°)^2/2g =40* (1/√2)^2=20m.
(2)

Rakesh roushan said:   3 years ago
Agree with you, thanks @Pkota.
(1)

Chandra mohan mahato said:   1 decade ago
Height of column should be 20 mtr.

Jwala said:   9 years ago
Answer 10 m.

Aditya Ch said:   9 years ago
Answer is correct.

Applying Pythagoras theorem, tan 45 = x/40, therefore x = 40 * 1 = 40.

Krishan Suthar said:   9 years ago
Yes, Correct @Aditya.

Krishan Suthar said:   9 years ago
Yes, Correct @Aditya.

Garry said:   8 years ago
The path of the particle will be a parabolic so tan θ will not be applied the correct answer from the projectile motion will come to be 20 m.

And I also agree @Mahato.

Jony said:   8 years ago
Please derive the expression @Garry.


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