Question

The length of a minute hand of a clock is 4 cm. Find the displacement and average velocity of the tip of the minute hand when it moves during a time interval from
(a) 3: 15 pm to 3 : 30 pm(b) 4: 15 pm to 4: 45 pm.

• A. (a) $\frac{\sqrt{2}}{225}cm{s}^{-1}$ (b) $\frac{2}{225}cm{s}^{-1}$
• B. (a) $\frac{\sqrt{3}}{225}cm{s}^{-1}$ (b) $\frac{1}{225}cm{s}^{-1}$
• C. (a) $\frac{\sqrt{2}}{225}cm{s}^{-1}$ (b) $\frac{1}{225}cm{s}^{-1}$
• D. (a) $\frac{\sqrt{12}}{225}cm{s}^{-1}$ (b) $\frac{2}{225}cm{s}^{-1}$

Answer 1

The correct option is C (a) $\frac{\sqrt{2}}{225}cm{s}^{-1}$ (b) $\frac{1}{225}cm{s}^{-1}$

Distance travelled$=(4^2+4^2{)}^{1/2}=4\sqrt{2}$

Time taken$=15\times 60=900s$

$v=\frac{4\sqrt{2}}{900}=\frac{\sqrt{2}}{225}m/s$

Total displacement $=8cm$

Time taken$=30\times 60=1800s$

$v=\frac{8}{1800}=\frac{1}{225}m/s$