A particle travels in a circle of radius 20 cm at a uniformly increasing speed. If the speed changes from 8ms-1 to 9ms-1 in 2s, what would be the angular acceleration (in rad s-2)? [UK PMT 2015]

Given, radius of the circle  =20cm=20×10−2mWhen speeds are 8ms-1 and 9ms-1 then angular speeds arerespectiveIy,  ω1=820×10−2=40rads−1and   ω2=920×10−2=45rads−1∴  Angular acceleration =ω2−ω1t=45−402=2.5rads−2