# 1) The angular velocity of a wheel is 70 rad/sec. If the radius of the wheel is 0.5 m, then linear velocity of the wheel is:{answer should come 35 m/s}2) The angular displacement of the minute hand of a clock in 20 minutes is:{answer should come radian}3) If the frequency of a particle performing circular motion increases from 60 rpm to 180 rpm in 20 seconds, its angular acceleration is :{answer should come 0.6284 }4) A flywheel rotates at a constant speed of 2400 rpm. The angle described by the shaft in radian in one second is :{answer should come 80 }

1
by jafiya

2014-09-28T03:04:23+05:30

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1. Angular velocity ω = 70 rad /sec
Rotations per second = n = ω / 2π  = 35/π per sec
linear velocity = distance covered in one rotation * n
= 2 π 0.5 * 35 / π = 35 m/sec

2. Angular displacement of minutes hand in 20 minutes
= total angle moved in one hour * 20 minutes / 60 minutes
= 2 π * 20 / 60 = 2 π /3
Minutes hand circles completely in 60 minutes. so angle covered = 2π

3.  ω = rpm * 2π / 60 radians/sec
ω2 - ω1 = 180 - 60 = 120 rpm = 120 * 2π / 60 = 4 π rad/sec
Angular acceleration = α = (ω2 - ω1) / time = 4π/20 = 0.6283 rad/sec²

4.  angle described in one second = ω * 1sec = rpm * (2π / 60) * 1 sec
= 2400 * 2π/60 = 80 π radians

thanx n u r welcom