Answer:
Option A
Explanation:
By force balancing perpendicular to the inclined plane
N=mgcosθ
By forces balancing parallel to inclined plane,
mgsinθ−fr=mdvdt
⇒dvdt=mgsinθ−frm⇒v(t)=∫gsinθdt−1m∫fr.dt
Now, torque, τ=Idωdt=r×Fr and I=mk2
∴ mk2dωdt=rFr or dωdt=rFrmk2
⇒ ω(t)=Rmk2∫frdt
or 1m∫frdt=k2Rω(t)=k2R2v(t) (using ω=v/R)
⇒ v(t)=∫gsinθdt−k2R2v(t)
or v(t)=1(1+k2R2)∫gsinθdt
So, acceleration,
a(t)=dv(t)dt=gsinθ(1+k2R2)