Cracking the SAT Physics Subject Test

B The cylinder slides across the surface with acceleration a = F/m until time t
= T, when a drops to zero (because F becomes zero). Therefore, from time t
= 0 to t = T, the velocity is steadily increasing (because the acceleration is a
positive constant), but, at t = T, the velocity remains constant. This is
illustrated in (B).

B We’ll use conservation of mechanical energy. Let the flat surface be our
PEgrav = 0 level. Then