Question: A thin uniform rod of length l cm and a small particle lie on a line separated by a distance of a cm. If K is a positive constant and F is measured in new tons, the gravitational force between them is
F = K/a(a + l)
(a) If a is increasing at the rate 2 cm/min when a = 15 and l = 5, how fast is F decreasing?
(b) If l is decreasing at the rate 2 cm/min when a = 15 and l = 5, how fast is F increasing?