y = 0 when sin (3
p
t - 2.4
p
) = 0
i.e., when 3
p
t - 2.4
p
= 0
t = 2.4/3 = 0.8 s
Of course it is also 0 every T (T = 0.667 s, see part b) from there.
i.e., 0.8 - 0.667 = 0.133 s
Is y increasing or decreasing as t is increased by
D
t at these points?
answer