<span>A tri-fold brochure has two parallel folds, splitting the brochure into three sections. Even when printed on low-weight paper, tri-folds can stand up easily, which makes them a great choice for displaying at conventions. You can fold both folds inwards so that the left and right sections of the brochure sit on top of one another, or you can have one fold inwards and the other outwards, to create an accordion effect, which looks very attractive.</span>
Well, Harry, what you said is not necessarily true the way you said it.
But we know what you mean, and what you meant to say is true.
The Doppler effect is observed if there is relative radial motion
between an object and an observer <em><u>AND</u></em> if the object happens
to be putting out sound or light in the observer's direction.
The work done on the sail is 600 J
Explanation:
The work done to lift the sail is equal to the gain in gravitational potential energy of the sail, therefore is:

where
m is the mass of the sail
g is the acceleration of gravity
(mg) is the weight of the sail
is the change in height of the sail
In this problem we have
mg = 150 N (weight)

Substituting, we find the work done:

Learn more about work:
brainly.com/question/6763771
brainly.com/question/6443626
#LearnwithBrainly