A wheel (to be considered as ring) of mass m and radius r rolls without sliding on a horizontal surface with constant velocity v. it encounters a step of height r/2 at which it ascends without sliding:
a.the angular velocity of the ring just after it comes in contact with the step is 3v/4r
b.the normal reaction due to the step on the wheel just after the impact is mg/2 - 9mv²/16r
c.the normal reaction due to the step on the wheel increases as the wheel ascends
d.the friction will be absent during the ascent.