You have to do the math of each and see which one adds up to 66.5
Answer:
The positive displacement from the midpoint of its motion at the speed equal one half of its maximum speed is 3.56 cm.
Explanation:
Maximum speed is :
v (max) = Aω
Speed v at any displacement y is given by
=
(
-
) ........................................................ i
And,
v =
v (max)
or, 2 × v = Aω .................................................... ii
Eliminating ω from equations i and ii,
=
(
-
)
or,
= (
)
=(
) 
or, y = 3.56 cm.
Answer: b
Explanation: the two pieces will repel as both have obtained a static charge.
V = f * wavelength
as we know electromagnetic wave has speed equal to light, so
3 * 10^8 = f * 1.3
f = 2.3 * 10^8 hertz
f = 230 mega hertz