To develop critical and analyzing skills
amongst her children, maths teacher showed her students a video of 3D objects and asked the students to
identify the 3D objects. One such video was of PWD workers constructing road using road roller. The
cylindrical road roller made of iron was 1m long. Its inner diameter was 54cm and thickness of the iron
sheet rolled into the road roller is 9cm.
1) What is the outer radius of the road roller ?
a) 22cm
b) 44cm
c) 36cm
d) 11cm
2) What is the outer curved surface area of the road roller ?
a) 1548π cm2
b) 220π cm2
c) 7200π cm2
d) 440π cm2
3) If PWD workers constructed 1584 m2
road in one day, find the number of revolutions that the
road roller made.
a) 500
b) 1000
c) 700
d) 100
4) What will be the amount of iron used in road roller ? ( take π = 3.14 )
a) 178038 cm3
b) 406944 cm3
c) 228906 cm3
d) 356076 cm3
5) If 1cc of iron weighs 10grams, what will be the weight of the road roller ? ( answer in kg )
a) 1780.38 kg
b) 4069.44 kg
c) 2089.06 kg
d) 3560.76 kg
Answers
Answer:
1) Option (c) 36cm is the correct option.
2) Option (c) 7200 π cm² is the correct option.
3) Option (c) 700 is the correct option.
4) Option (a) 178038cm³ is the correct option.
5) Option (a) 1780.38 kg is the correct option.
Step-by-step explanation:
Given:
Length of the roller = 1m
Inner diameter = 54 cm
Thickness of the iron sheet = 9 cm
1) Outer radius = Inner radius + Thickness
= 54/2cm + 9cm
= 27cm + 9 cm
= 36cm
Option (c) 36cm is the correct option.
2) Outer curved surface = 2πrh
= 2π*36*100
= 7200 π cm²
Option (c) 7200 π cm² is the correct option.
3) Area covered = 1584m²
We know that Area = Outer CSA * No. of revolutions
=> 1584m² = 7200 π cm² * no. of revolutions
=> No. of revolutions = 1584/7200π
=
= 700
Therefore, 700 revolutions will be made.
Option (c) 700 is the correct option.
4) Amount of iron used = Volume of iron used
= Outer volume - Inner volume
= πR²h - πr²h
= πh(R² - r²)
= 3.14 * 100 (36² - 27²)
= 314 * (1296 - 729)
= 178038cm³
Option (a) 178038cm³ is the correct option.
5) 1cc of iron weighs 10 gram
=> 178038cc of iron will weigh = 178038*10
= 1780380 gram
= 1780.38 kg (1kg = 1000gm)
Option (a) 1780.38 kg is the correct option.
Answer:
Step-by-step explanation:
36cm