Weight = (mass) x (gravity)
Weight = (8 x 10⁻⁴ kg) x (10 N/kg) = 0.008 Newton
The primary source would be the original article published in a scientific journal. All other choices would be based on information from the original article.
Newspapers would only pick up the information from the journal itself, or from the authors. Books follow after the original article, after it has gained momentum among the research community. The public lecture at a museum would be based on work from the journal article.
Here we will the speed of seagull which is v = 9 m/s
this is the speed of seagull when there is no effect of wind on it
now in part a)
if effect of wind is in opposite direction then it travels 6 km in 20 min
so the average speed is given by the ratio of total distance and total time
now since effect of wind is in opposite direction then we can say
Part b)
now if bird travels in the same direction of wind then we will have
now we can find the time to go back
Part c)
Total time of round trip when wind is present
now when there is no wind total time is given by
So due to wind time will be more
Work = (force) x (distance) =
(200 N) x (3.5 m) = <em>700 joules</em>