Defence Exam  >  Defence Questions  >  A given quantity of metal is to be cast into ... Start Learning for Free
A given quantity of metal is to be cast into a half cylinder (i.e. with a rectangular base and semicircular ends). If the total surface area is to be minimum, then the ratio of the height of the half cylinder to the diameter of the semicircular ends is
  • a)
    π ∶ (π + 2)
  • b)
    (π + 2) ∶ π
  • c)
    1 : 1
  • d)
    None of the above
Correct answer is option 'A'. Can you explain this answer?
Verified Answer
A given quantity of metal is to be cast into a half cylinder (i.e. wit...
View all questions of this test
Most Upvoted Answer
A given quantity of metal is to be cast into a half cylinder (i.e. wit...
To find the ratio of the height of the half cylinder to the diameter of the semicircular ends, we need to minimize the surface area.

Let's assume the height of the half cylinder is h, and the diameter of the semicircular ends is d.

The surface area of the half cylinder consists of the area of the rectangular base, the areas of the two semicircular ends, and the area of the curved surface.

The area of the rectangular base is given by A_rectangular = h * d.

The areas of the two semicircular ends are given by A_semicircular = 2 * (π * (d/2)^2)/2 = (π * d^2)/4.

The area of the curved surface is given by A_curved = (π * d * h)/2.

Therefore, the total surface area is A_total = A_rectangular + A_semicircular + A_curved = h * d + (π * d^2)/4 + (π * d * h)/2.

To minimize the surface area, we need to find the values of h and d that minimize A_total.

Taking the derivative of A_total with respect to h, we get d + (π * d)/2 = 0.

Simplifying this equation, we have d(1 + π/2) = 0.

Since d cannot be equal to zero, we have 1 + π/2 = 0.

Solving for π, we get π = -2.

However, this is not a valid value for π, so there is no minimum surface area.

Therefore, we cannot determine the ratio of the height of the half cylinder to the diameter of the semicircular ends.
Explore Courses for Defence exam
A given quantity of metal is to be cast into a half cylinder (i.e. with a rectangular base and semicircular ends). If the total surface area is to be minimum, then the ratio of the height of the half cylinder to the diameter of the semicircular ends isa)π (π + 2)b)(π + 2) πc)1 : 1d)None of the aboveCorrect answer is option 'A'. Can you explain this answer?
Question Description
A given quantity of metal is to be cast into a half cylinder (i.e. with a rectangular base and semicircular ends). If the total surface area is to be minimum, then the ratio of the height of the half cylinder to the diameter of the semicircular ends isa)π (π + 2)b)(π + 2) πc)1 : 1d)None of the aboveCorrect answer is option 'A'. Can you explain this answer? for Defence 2024 is part of Defence preparation. The Question and answers have been prepared according to the Defence exam syllabus. Information about A given quantity of metal is to be cast into a half cylinder (i.e. with a rectangular base and semicircular ends). If the total surface area is to be minimum, then the ratio of the height of the half cylinder to the diameter of the semicircular ends isa)π (π + 2)b)(π + 2) πc)1 : 1d)None of the aboveCorrect answer is option 'A'. Can you explain this answer? covers all topics & solutions for Defence 2024 Exam. Find important definitions, questions, meanings, examples, exercises and tests below for A given quantity of metal is to be cast into a half cylinder (i.e. with a rectangular base and semicircular ends). If the total surface area is to be minimum, then the ratio of the height of the half cylinder to the diameter of the semicircular ends isa)π (π + 2)b)(π + 2) πc)1 : 1d)None of the aboveCorrect answer is option 'A'. Can you explain this answer?.
Solutions for A given quantity of metal is to be cast into a half cylinder (i.e. with a rectangular base and semicircular ends). If the total surface area is to be minimum, then the ratio of the height of the half cylinder to the diameter of the semicircular ends isa)π (π + 2)b)(π + 2) πc)1 : 1d)None of the aboveCorrect answer is option 'A'. Can you explain this answer? in English & in Hindi are available as part of our courses for Defence. Download more important topics, notes, lectures and mock test series for Defence Exam by signing up for free.
Here you can find the meaning of A given quantity of metal is to be cast into a half cylinder (i.e. with a rectangular base and semicircular ends). If the total surface area is to be minimum, then the ratio of the height of the half cylinder to the diameter of the semicircular ends isa)π (π + 2)b)(π + 2) πc)1 : 1d)None of the aboveCorrect answer is option 'A'. Can you explain this answer? defined & explained in the simplest way possible. Besides giving the explanation of A given quantity of metal is to be cast into a half cylinder (i.e. with a rectangular base and semicircular ends). If the total surface area is to be minimum, then the ratio of the height of the half cylinder to the diameter of the semicircular ends isa)π (π + 2)b)(π + 2) πc)1 : 1d)None of the aboveCorrect answer is option 'A'. Can you explain this answer?, a detailed solution for A given quantity of metal is to be cast into a half cylinder (i.e. with a rectangular base and semicircular ends). If the total surface area is to be minimum, then the ratio of the height of the half cylinder to the diameter of the semicircular ends isa)π (π + 2)b)(π + 2) πc)1 : 1d)None of the aboveCorrect answer is option 'A'. Can you explain this answer? has been provided alongside types of A given quantity of metal is to be cast into a half cylinder (i.e. with a rectangular base and semicircular ends). If the total surface area is to be minimum, then the ratio of the height of the half cylinder to the diameter of the semicircular ends isa)π (π + 2)b)(π + 2) πc)1 : 1d)None of the aboveCorrect answer is option 'A'. Can you explain this answer? theory, EduRev gives you an ample number of questions to practice A given quantity of metal is to be cast into a half cylinder (i.e. with a rectangular base and semicircular ends). If the total surface area is to be minimum, then the ratio of the height of the half cylinder to the diameter of the semicircular ends isa)π (π + 2)b)(π + 2) πc)1 : 1d)None of the aboveCorrect answer is option 'A'. Can you explain this answer? tests, examples and also practice Defence tests.
Explore Courses for Defence exam
Signup for Free!
Signup to see your scores go up within 7 days! Learn & Practice with 1000+ FREE Notes, Videos & Tests.
10M+ students study on EduRev