Question

A cylinder of circumference 8 cm and length 21 cm rolls without sliding for $4\frac{1}{2}$ seconds at the rate of 9 complete rounds per second.
The area covered by the cylinder in $4\frac{1}{2}$ seconds
Area covered by the cylinder in 1 round = its curved surface area

Answer 1

Given,

Distance travelled by the cylinder in $1$ round = it's circumference

Distance travelled in $4.5=4.5\times$ Distance covered in $1sec$

$=4.5\times 9\times 8$

$=324cm$

Hence, this is the answer.