Question

A person moved from A to B on a circular path as shown in figure If the distance travelled by him is 60 m, then the magnitude of displacement would be Given ( Cos 135° = -0.7)

• A. 42 m
• B. 47 m
• C. 19 m
• D. 40 m

Answer 1

Answer: (B)

47 m

Answer 2

Distance = $60$ $m$

⇒ Angle = $135\degree$

Displacement $AB$ = $\sqrt{R^2 + R^2 - 2R^2\cos 135° }$

$= 2\left(\frac{60}{135} \times \frac {180}\pi\right) \left[\frac{1- \cos (135°)}2\right]^{1/2}$

$= 2(\frac{80}\pi) (0.85)^{1/2}$

Hence, the displacement is $47\; m$.