Which of the following is the best definition of nodes? a. places of constructive interference in a standing wave b. places where two waves are added to each other c. places where one wave blocks another d. places where a standing wave remains fixed in space

D. place where a standing wave remains fixed in space.

Explanation:

A node is point where the amplitude of wave will be zero.But on the other hand a point where amplitude of wave is maximum is called anti node .When two wave superimpose then they form node and anti node continuously.

So we can say that ,a node is a place where a standing wave remains fixed in space.Stationary wave is called standing wave.

a: 45.9 meters

b: 4.29 seconds

step-by-step explanation:

a: h(t)=1/2(-9.8)(3)^2+0(3)+90

h(t)=-4.9(3)^2+90

h(t)=-44.1+90

h(t)=45.9 meters

b: 0=1/2(-9.8)(t^2)+0t+90

0=-4.9t^2+90

-90=-4.9t^2

18.37=t^2

t=4.29 seconds

in the second question, the numbers aren't exact, but they're a close approximation.