Ahelicopter is hovering motionless above a disabled boat, while rescue workers use a rope to lift an injured sailor. while that sailor is being lifted upward, the net force on the motionless helicopter is(a) downward and equal to the sailor's weight. (b) zero. (c) upward and equal to the sailor's weight. (d) downward and equal to the sailor's weight plus the helicopter's weight.

The keyword for the solution of this problem is the word “motionless”. We are told here that the helicopter is motionless, this means (according to Newton’s 1st law of motion) the net force on the helicopter is zero.

Now, if we want to go further in the analysis, we can draw a Free Body Diagram (FBD) of this situation (figure attached), assuming there are no forces in the x-axis.

Nevertheless, in the y-axis we have the weight which is equal to the weight of the helicopter plus the weight of the sailor (assuming the rope is weightless):

And the lift force  which is with the same magnitude but in the opposite direction of the weight:

Therefore, the correct option is B.

as we probably am aware that our atmosphere or air have various levels, each level has different gasses, and each gas has another porousness. at the point when the light originates from lower porousness to higher penetrability, it alters its course. with the goal that implies that when the light originates from the moon to the earth, it alters it's course a lot more occasions. it essentially implies that the state of the light piece of the moon is changed on the earth.

not copied too! hope this !

joke:

h o h o hope you have a merry christmas!