1. A particle moves on a line according to the law s=f(t) so that its velocity v=ks, where k is a nonzero constant. Its acceleration is
(E) none of these
2. As the tides change, the water-level in a bay varies sinusoidally. At high tide today at 8 A.M., the water-level was 15 feet; at low tide, 6 hours later at 2 P.M., it was 3 feet. How fast , in ft per hr, was the water-level dropping at noon today?
(B) (π√ 3)/2
(C) 3√ 3
(D) π√ 3
(E) 6√ 3
if you could answer any of these question, help me please