Aptitude - Volume and Surface Area - Discussion
Discussion Forum : Volume and Surface Area - General Questions (Q.No. 5)
5.
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:
Answer: Option
Explanation:
External radius = 4 cm,
Internal radius = 3 cm.
| Volume of iron |
|
||||||
|
|||||||
| = 462 cm3. |
cm3
Weight of iron = (462 x 8) gm = 3696 gm = 3.696 kg.
Discussion:
60 comments Page 3 of 6.
Indranath said:
8 years ago
Why not (4-3)^2?
Dhana reddy said:
8 years ago
Why 4^2 -3^2? Please explain this step.
Lavanya said:
8 years ago
Thank you, well explained @Dhinesh.
Deepak M said:
8 years ago
Thank you all.
Mritunjay said:
8 years ago
1dm=how many metre
Rohan said:
7 years ago
How did you find out the DENSITY = 8? Please explain.
Prasanth said:
7 years ago
Convert hollow cylinder into the metal sheet.
Hollow cylinder
h=21cm
Thickness=1cm
Metal sheet
b=21cm
h=1cm
loop length of the cylinder will become the length of the metal sheet.
The loop length=2*π*r, r=4cm.
The volume of metal sheet
= lbh = (2*π*4)*21*1=527.52 cu.cm.
weight=8*527.52=4220.16 gm=4.220 kg
is this wrong? if this so, explain me.
Hollow cylinder
h=21cm
Thickness=1cm
Metal sheet
b=21cm
h=1cm
loop length of the cylinder will become the length of the metal sheet.
The loop length=2*π*r, r=4cm.
The volume of metal sheet
= lbh = (2*π*4)*21*1=527.52 cu.cm.
weight=8*527.52=4220.16 gm=4.220 kg
is this wrong? if this so, explain me.
CHINMAYE said:
7 years ago
@Rohan.
It's given in the question that iron weighs 8 g/cm3. It's nothing but a density.
It's given in the question that iron weighs 8 g/cm3. It's nothing but a density.
Rahul said:
6 years ago
There is a formula for hollow sphere 3.14 (R^2-r^2)h.
Sunil said:
6 years ago
Why 4 square minus 3 square equals to 7 * 1.
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