Question

9. A cylinder of circumference 10 cm and height 22 cm rolls without sliding for
5 seconds at the rate of 5 complete rounds per second. Find the area covered
2
by the cylinder in 5 seconds .​

Answer 1

Given

✭ Circumference of a cylinder is 10cm

✭ Height of the cylinder is 22 cm

✭ It completes 5 rounds per second for 5 seconds

To Find

◈ The area covered?

Solution

We know that CSA of cylinder is given by,

CSA = 2πrh

So first let's find the radius,

➝ 2πr = Circumference

➝ 2 × 22/7 × r = 10

➝ r = 10 × 7/44

➝ r = 1.59 cm

Substituting this in the formula for CSA

➳ CSA = 2πrh

➳ CSA = 2 × 22/7 × 1.59 × 22

➳ CSA = 219.88 cm²

So on in one second if it take 5 rounds

»» 219.88 × 5

»» 1099.4 cm²/sec

Now in 5 Seconds

⪼ 1099.4 × 5

⪼ 5497 cm²

━━━━━━━━━━━━━━━━

Answer 2

Answer:

✬ LSA = 220 cm² ✬

Step-by-step explanation:

Given:

Circumference of base of right circular cylinder is 44 cm.

Measure of height of cylinder is 5 cm.

To Find:

What is the lateral surface area of cylinder ?

Solution: Let the meaure of radius of cylinder be r cm.

➟ Circumference of circular cylinder = 44 cm

➟ 2πr = 44

➟ 2(22/7)r = 44

➟ 44r/7 = 44

➟ r = 44(7)/44

➟ r = 7 cm

Now, we have

Radius of cylinder = 7 cm

Height of cylinder = 5 cm

As we know that

★ LSA of Cylinder = 2πrh ★

⟹ LSA = 2(22/7)(7)(5)

⟹ LSA = 44/7(35)

⟹ LSA = 44

$× 5$

⟹ LSA = 220

Hence, the lateral surface area of right circular cylinder is 220 cm².