Question

Find the number of right angles turned through by the hour hand of a clock when it goes from $5$ to $11$.

Answer 1

Step 1. Find the total angle covered

In the concept of revolution and clockwise rotation, the hour hand of the clock revolves by $360°$or $4$ at right angles in a $1$complete round.

From $5$ to$11$, the hour hand has traveled $6$ hours

There are total $12$ hours written on a clock, and by covering $12$ hours, an hour hand has covered $360°$ (a circle) or a clock is a complete circle having $360°$ and it is divided into $12$ equal parts, i.e. each part is,

$\frac{360}{12}=30°$

On $1$hour travel hour hand turns $30°$

So, for traveling $6$ hours on hour hand will cover,

$30°\times 6=180°$

Step 2. Find the number of right angles

$1$ right angle $=90°$

Therefore $180°$ is $\frac{180°}{90°}=2$ right angles

The hour hand turned by $2$ right angles.

Hence, the hour hand turns through $2$ right angles starting from $5$ to$11$.