Question

A clock has its second hand 2.0 cm long.Find the average speed and modulus of average velocity of the second hand in 15s.

Answer 1

In 15 second the angle it taverse is 90 degree or π/2 radian

The arc length the tip travels is 2* π/2 = π cm ( Quarter of a circle = 2 π R / 4 = π cm )

Hence the average speed of the tip = distance / time = (π/ 15) cm /s

0.21 cm /s
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To find the modulus of average velocity

Average velocity = displacemet / time =

The displacement is the hypotenuse of the right angled triangle of side 2 cm

Displacement = √ ( 2^2 + 2^2) = 2.83 cm

Average velocity = 2.83 / 15 = 0.19 cm /s