Question

Which of the following is an example of rotational motion?
$i)$ Motion of an electron around the nucleus.
$ii)$ Motion of the cap of a water bottle when it is being opened.
$iii)$ Motion of a fan.
$iv)$ Motion of the clothes inside a washing machine.
$v)$ A vehicle moving along the circumference of a circle

• A. $\left(i\right),\left(iii\right)$ and $\left(v\right)$
• B. $\left(i\right)$ and $\left(iv\right)$
• C. $\left(ii\right)$ and $\left(iii\right)$
• D. $\left(ii\right)$ and $\left(iv\right)$

Answer 1

The correct option is C $\left(ii\right)$ and $\left(iii\right)$

The axis about which electrons revolves passes through its nucleus. Hence it is a circular motion but not rotational motion.
When we remove the cap of a water bottle, the cap spins about its own axis. This is an example of rotation motion.
The blades of a fan rotate about the fan’s axis. This is rotational motion.
The clothes inside a washing machine rotate about the centre of the cylinder of the washing machine. The axis of rotation lie outside the clothes themselves. Hence this is not rotational motion.
A vehicle moving along a circle is rotating about the centre of the circle. This is a circular motion and not rotational motion.