A table clock has its minute hand 5.0 cm long'. The average velocity of the tip of the minute hand between ` 6.00 am` to ' 6.30 pm' is.

Options

A. ` 4.4 xx10^(-3), 1.8 xx 10^(-4)`
B. `1.8 xx 10^(-4), 4,4 xx 10^(-3)`
C. `8xx 10^(-3) , 4.4 xx 10^(-3)`
D. `4.4 xx 10^(3) , 8xx 10^(-4)`

Explanation

At 6.00 a.m. the tip of the minute hand is at 12
mark and at 6.30 a.m. or 6.30 p.m. it is `180^(0)` away.
Thus the straight line distance between the initial
and final positions of the tip is equal to the diameter
of the clock.
Displacement = 2 R ` = 2 xx 4 cm = 8 cm `
Time taken from 6 a.m. to 6.30 a.m. is 30
minutes = 1800 x . The average velocity is
` V_(av) = ("Displacement")/( "time") = (8.0 cm)/(1800 s ) = 4.4 xx 10^(-3) cm//s `
Again time taken from 6 am to 6.30 p.m.
= 12 hrs + 30 minutes = 45000 s
` therefore V_(av) = ("Displacement ")/("time") = (8)/(45000) = 1.8xx 10^(-4) cm//s `
Hence correct anser is (A)