Class 7 Exam > Class 7 Questions > A hollow iron pipe is 21 cm long and its exte...
Start Learning for Free
A hollow iron pipe is 21 cm long and its external diameter is 8 cm. If the thickness of the pipe is 1 cm and iron weighs 8 g/cm3, then the weight of the pipe is:
- a)3.6 kg
- b)3.696 kg
- c)36 kg
- d)36.9 kg
Correct answer is option 'B'. Can you explain this answer?
Verified Answer
A hollow iron pipe is 21 cm long and its external diameter is 8 cm. If...
External radius = 4 cm,
Internal radius = 3 cm.
Volume of iron
= (22/7 × [(4)2 – (3)2] × 21) cm3
= (22/7 × 7 × 1 × 21) cm3
= 462 cm3
∴ Weight of iron= (462 × 8) gm
= 3696 gm
= 3.696 kg
Internal radius = 3 cm.
Volume of iron
= (22/7 × [(4)2 – (3)2] × 21) cm3
= (22/7 × 7 × 1 × 21) cm3
= 462 cm3
∴ Weight of iron= (462 × 8) gm
= 3696 gm
= 3.696 kg
Most Upvoted Answer
A hollow iron pipe is 21 cm long and its external diameter is 8 cm. If...
Given Data
- Length of the pipe (L) = 21 cm
- External diameter (D) = 8 cm
- Thickness of the pipe (t) = 1 cm
- Density of iron = 8 g/cm³
Calculating Dimensions
- External Radius (R):
R = D/2 = 8/2 = 4 cm
- Internal Diameter (d):
d = D - 2*t = 8 - 2*1 = 6 cm
- Internal Radius (r):
r = d/2 = 6/2 = 3 cm
Volume of the Pipe
- External Volume (V_external):
V_external = π * R² * L
= π * (4 cm)² * 21 cm
= 336π cm³
- Internal Volume (V_internal):
V_internal = π * r² * L
= π * (3 cm)² * 21 cm
= 189π cm³
- Volume of the Iron (V_iron):
V_iron = V_external - V_internal
= 336π cm³ - 189π cm³
= 147π cm³
Weight of the Pipe
- Weight (W):
W = V_iron * Density
= 147π cm³ * 8 g/cm³
= 1176π g
= 3696 g
= 3.696 kg
Conclusion
The weight of the hollow iron pipe is 3.696 kg, which corresponds to option B.
- Length of the pipe (L) = 21 cm
- External diameter (D) = 8 cm
- Thickness of the pipe (t) = 1 cm
- Density of iron = 8 g/cm³
Calculating Dimensions
- External Radius (R):
R = D/2 = 8/2 = 4 cm
- Internal Diameter (d):
d = D - 2*t = 8 - 2*1 = 6 cm
- Internal Radius (r):
r = d/2 = 6/2 = 3 cm
Volume of the Pipe
- External Volume (V_external):
V_external = π * R² * L
= π * (4 cm)² * 21 cm
= 336π cm³
- Internal Volume (V_internal):
V_internal = π * r² * L
= π * (3 cm)² * 21 cm
= 189π cm³
- Volume of the Iron (V_iron):
V_iron = V_external - V_internal
= 336π cm³ - 189π cm³
= 147π cm³
Weight of the Pipe
- Weight (W):
W = V_iron * Density
= 147π cm³ * 8 g/cm³
= 1176π g
= 3696 g
= 3.696 kg
Conclusion
The weight of the hollow iron pipe is 3.696 kg, which corresponds to option B.
|
Explore Courses for Class 7 exam
|
|
Top Courses for Class 7View all
Question Description
A hollow iron pipe is 21 cm long and its external diameter is 8 cm. If the thickness of the pipe is 1 cm and iron weighs 8 g/cm3, then the weight of the pipe is:a)3.6 kgb)3.696 kgc)36 kgd)36.9 kgCorrect answer is option 'B'. Can you explain this answer? for Class 7 2025 is part of Class 7 preparation. The Question and answers have been prepared according to the Class 7 exam syllabus. Information about A hollow iron pipe is 21 cm long and its external diameter is 8 cm. If the thickness of the pipe is 1 cm and iron weighs 8 g/cm3, then the weight of the pipe is:a)3.6 kgb)3.696 kgc)36 kgd)36.9 kgCorrect answer is option 'B'. Can you explain this answer? covers all topics & solutions for Class 7 2025 Exam. Find important definitions, questions, meanings, examples, exercises and tests below for A hollow iron pipe is 21 cm long and its external diameter is 8 cm. If the thickness of the pipe is 1 cm and iron weighs 8 g/cm3, then the weight of the pipe is:a)3.6 kgb)3.696 kgc)36 kgd)36.9 kgCorrect answer is option 'B'. Can you explain this answer?.
A hollow iron pipe is 21 cm long and its external diameter is 8 cm. If the thickness of the pipe is 1 cm and iron weighs 8 g/cm3, then the weight of the pipe is:a)3.6 kgb)3.696 kgc)36 kgd)36.9 kgCorrect answer is option 'B'. Can you explain this answer? for Class 7 2025 is part of Class 7 preparation. The Question and answers have been prepared according to the Class 7 exam syllabus. Information about A hollow iron pipe is 21 cm long and its external diameter is 8 cm. If the thickness of the pipe is 1 cm and iron weighs 8 g/cm3, then the weight of the pipe is:a)3.6 kgb)3.696 kgc)36 kgd)36.9 kgCorrect answer is option 'B'. Can you explain this answer? covers all topics & solutions for Class 7 2025 Exam. Find important definitions, questions, meanings, examples, exercises and tests below for A hollow iron pipe is 21 cm long and its external diameter is 8 cm. If the thickness of the pipe is 1 cm and iron weighs 8 g/cm3, then the weight of the pipe is:a)3.6 kgb)3.696 kgc)36 kgd)36.9 kgCorrect answer is option 'B'. Can you explain this answer?.
Solutions for A hollow iron pipe is 21 cm long and its external diameter is 8 cm. If the thickness of the pipe is 1 cm and iron weighs 8 g/cm3, then the weight of the pipe is:a)3.6 kgb)3.696 kgc)36 kgd)36.9 kgCorrect answer is option 'B'. Can you explain this answer? in English & in Hindi are available as part of our courses for Class 7.
Download more important topics, notes, lectures and mock test series for Class 7 Exam by signing up for free.
Here you can find the meaning of A hollow iron pipe is 21 cm long and its external diameter is 8 cm. If the thickness of the pipe is 1 cm and iron weighs 8 g/cm3, then the weight of the pipe is:a)3.6 kgb)3.696 kgc)36 kgd)36.9 kgCorrect answer is option 'B'. Can you explain this answer? defined & explained in the simplest way possible. Besides giving the explanation of
A hollow iron pipe is 21 cm long and its external diameter is 8 cm. If the thickness of the pipe is 1 cm and iron weighs 8 g/cm3, then the weight of the pipe is:a)3.6 kgb)3.696 kgc)36 kgd)36.9 kgCorrect answer is option 'B'. Can you explain this answer?, a detailed solution for A hollow iron pipe is 21 cm long and its external diameter is 8 cm. If the thickness of the pipe is 1 cm and iron weighs 8 g/cm3, then the weight of the pipe is:a)3.6 kgb)3.696 kgc)36 kgd)36.9 kgCorrect answer is option 'B'. Can you explain this answer? has been provided alongside types of A hollow iron pipe is 21 cm long and its external diameter is 8 cm. If the thickness of the pipe is 1 cm and iron weighs 8 g/cm3, then the weight of the pipe is:a)3.6 kgb)3.696 kgc)36 kgd)36.9 kgCorrect answer is option 'B'. Can you explain this answer? theory, EduRev gives you an
ample number of questions to practice A hollow iron pipe is 21 cm long and its external diameter is 8 cm. If the thickness of the pipe is 1 cm and iron weighs 8 g/cm3, then the weight of the pipe is:a)3.6 kgb)3.696 kgc)36 kgd)36.9 kgCorrect answer is option 'B'. Can you explain this answer? tests, examples and also practice Class 7 tests.
|
|
Explore Courses for Class 7 exam
|
|
Signup for Free!
Signup to see your scores go up within 7 days! Learn & Practice with 1000+ FREE Notes, Videos & Tests.
|
© EduRev
|
Education Revolution
|
|
Signup on EduRev and stay on top of your study goals
10M+ students crushing their study goals daily