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# The length of the seconds hand in a wall clock is 10 cm. The magnitude of velocity and acceleration of its tip are

A
102 m/s and 103 m/s2
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B
102 m/s and 104 m/s2
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C
101 m/s and 102 m/s2
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D
102 m/s and 102 m/s2
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Solution

## The correct option is A 10−2 m/s and 10−3 m/s2The seconds hand of a clock completes one revolution in 60 s. Therefore, frequency f=160 Hz The angular velocity of the seconds hand is given by ω=2πf=2π60=π30 rad/s The tip of the seconds hand is at a distance r=10 cm=0.1 m from the axis of rotation. Thus, linear velocity of the tip is given by v=ωr=(π30)(0.1)≈0.01=10−2 m/s The direction of the velocity is tangential. The tip moves in a circle of radius r=0.1 m with a constant speed v=10−2 m/s . Thus, tangential acceleration of the tip is zero and its radial (centripetal) acceleration is ac=v2r=(0.01)20.1=0.001=10−3 m/s2 The direction of centripetal acceleration is radially inward. Hence option A is the correct answer.  Suggest Corrections  2      Similar questions  Related Videos   Relative
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